[feat] Linter documentation in GitHub Pages. (#263)

This (incredibly large) PR adds a `docs/` directory that we can
serve with GitHub Pages.

It provides documentation for three linter rules; the remainder
will come in follow-up PRs.

Note that as part of this, I intend to enforce (and soon lint for)
some consistency on linter rules, including:

- One rule per file.
- The rule's filename must be derived from the rule name
  (converting `-` to `_` but no other changes).

This is to make things like "View Implmenetation" easy.

.gitignore

@@ -1,2 +1,7 @@
 .idea
-.vscode
+.vscode
+
+# Jekyll
+docs/default.profraw
+docs/_site
+docs/.jekyll-metadata

docs/.dockerignore

@@ -0,0 +1,35 @@
+# Version control scaffolding
+.git
+.gitignore
+
+# Docker scaffolding
+Dockerfile
+.dockerignore
+
+# Ruby & Jekyll scaffolding
+_site
+
+# Translations
+*.mo
+
+# Mac
+.DS_Store
+
+# Mr Developer
+.mr.developer.cfg
+.project
+.pydevproject
+
+# JetBrains
+.idea
+
+# Built documentation
+docs/_build
+docs/_build_doc2dash
+
+# Virtual environment
+env/
+coverage.xml
+
+# Jekyll metadata
+.jekyll-metadata

docs/.gitignore

@@ -0,0 +1,4 @@
+# Jekyll
+default.profraw
+_site
+.jekyll-metadata

docs/.prettierignore

@@ -0,0 +1,3 @@
+_includes/aip-nav.html
+_includes/svgs.html
+_sass/colors.scss

docs/.prettierrc.yaml

@@ -0,0 +1,5 @@
+---
+printWidth: 79
+proseWrap: always
+singleQuote: true
+trailingComma: es5

docs/Dockerfile

@@ -0,0 +1,34 @@
+FROM ruby:2.6-alpine
+
+# Copy the existing code into the Docker image.
+#
+# This will copy everything *at build time* (not at runtime), so it is
+# still important to use `--mount` to get a reasonable development loop.
+# This makes the image work for both purposes, though.
+COPY . /code/
+WORKDIR /code/
+
+# Install bundler and gems for this project.
+RUN echo "gem: --no-ri --no-rdoc" > ~/.gemrc && \
+  apk add --no-cache alpine-sdk && \
+  gem update --system && \
+  gem install bundler && \
+  bundle install && \
+  apk del --no-cache alpine-sdk && \
+  rm ~/.gemrc
+
+# Install git. (Jekyll expects it.)
+RUN apk add --no-cache git
+
+# Set environment variables that GitHub Pages expects.
+ENV PAGES_REPO_NWO googleapis/googleapis.github.io
+
+# Expose appropriate ports.
+EXPOSE 4000
+EXPOSE 35729
+
+# Run Jekyll's dev server.
+# Reminder: Use -p with `docker run` to publish ports.
+ENTRYPOINT ["bundle", "exec", "jekyll", "serve", \
+  "--destination", "/site", \
+  "--host", "0.0.0.0"]

docs/Gemfile

@@ -0,0 +1,4 @@
+source "https://rubygems.org" do
+  gem "jekyll"
+  gem "github-pages", group: :jekyll_plugins
+end

docs/Gemfile.lock

@@ -0,0 +1,249 @@
+GEM
+  remote: https://rubygems.org/
+  specs:
+    activesupport (4.2.10)
+      i18n (~> 0.7)
+      minitest (~> 5.1)
+      thread_safe (~> 0.3, >= 0.3.4)
+      tzinfo (~> 1.1)
+    addressable (2.5.2)
+      public_suffix (>= 2.0.2, < 4.0)
+    coffee-script (2.4.1)
+      coffee-script-source
+      execjs
+    coffee-script-source (1.11.1)
+    colorator (1.1.0)
+    commonmarker (0.17.13)
+      ruby-enum (~> 0.5)
+    concurrent-ruby (1.1.5)
+    dnsruby (1.61.2)
+      addressable (~> 2.5)
+    em-websocket (0.5.1)
+      eventmachine (>= 0.12.9)
+      http_parser.rb (~> 0.6.0)
+    ethon (0.12.0)
+      ffi (>= 1.3.0)
+    eventmachine (1.2.7)
+    execjs (2.7.0)
+    faraday (0.15.4)
+      multipart-post (>= 1.2, < 3)
+    ffi (1.10.0)
+    forwardable-extended (2.6.0)
+    gemoji (3.0.0)
+    github-pages (197)
+      activesupport (= 4.2.10)
+      github-pages-health-check (= 1.16.1)
+      jekyll (= 3.7.4)
+      jekyll-avatar (= 0.6.0)
+      jekyll-coffeescript (= 1.1.1)
+      jekyll-commonmark-ghpages (= 0.1.5)
+      jekyll-default-layout (= 0.1.4)
+      jekyll-feed (= 0.11.0)
+      jekyll-gist (= 1.5.0)
+      jekyll-github-metadata (= 2.12.1)
+      jekyll-mentions (= 1.4.1)
+      jekyll-optional-front-matter (= 0.3.0)
+      jekyll-paginate (= 1.1.0)
+      jekyll-readme-index (= 0.2.0)
+      jekyll-redirect-from (= 0.14.0)
+      jekyll-relative-links (= 0.6.0)
+      jekyll-remote-theme (= 0.3.1)
+      jekyll-sass-converter (= 1.5.2)
+      jekyll-seo-tag (= 2.5.0)
+      jekyll-sitemap (= 1.2.0)
+      jekyll-swiss (= 0.4.0)
+      jekyll-theme-architect (= 0.1.1)
+      jekyll-theme-cayman (= 0.1.1)
+      jekyll-theme-dinky (= 0.1.1)
+      jekyll-theme-hacker (= 0.1.1)
+      jekyll-theme-leap-day (= 0.1.1)
+      jekyll-theme-merlot (= 0.1.1)
+      jekyll-theme-midnight (= 0.1.1)
+      jekyll-theme-minimal (= 0.1.1)
+      jekyll-theme-modernist (= 0.1.1)
+      jekyll-theme-primer (= 0.5.3)
+      jekyll-theme-slate (= 0.1.1)
+      jekyll-theme-tactile (= 0.1.1)
+      jekyll-theme-time-machine (= 0.1.1)
+      jekyll-titles-from-headings (= 0.5.1)
+      jemoji (= 0.10.2)
+      kramdown (= 1.17.0)
+      liquid (= 4.0.0)
+      listen (= 3.1.5)
+      mercenary (~> 0.3)
+      minima (= 2.5.0)
+      nokogiri (>= 1.8.5, < 2.0)
+      rouge (= 2.2.1)
+      terminal-table (~> 1.4)
+    github-pages-health-check (1.16.1)
+      addressable (~> 2.3)
+      dnsruby (~> 1.60)
+      octokit (~> 4.0)
+      public_suffix (~> 3.0)
+      typhoeus (~> 1.3)
+    html-pipeline (2.10.0)
+      activesupport (>= 2)
+      nokogiri (>= 1.4)
+    http_parser.rb (0.6.0)
+    i18n (0.9.5)
+      concurrent-ruby (~> 1.0)
+    jekyll (3.7.4)
+      addressable (~> 2.4)
+      colorator (~> 1.0)
+      em-websocket (~> 0.5)
+      i18n (~> 0.7)
+      jekyll-sass-converter (~> 1.0)
+      jekyll-watch (~> 2.0)
+      kramdown (~> 1.14)
+      liquid (~> 4.0)
+      mercenary (~> 0.3.3)
+      pathutil (~> 0.9)
+      rouge (>= 1.7, < 4)
+      safe_yaml (~> 1.0)
+    jekyll-avatar (0.6.0)
+      jekyll (~> 3.0)
+    jekyll-coffeescript (1.1.1)
+      coffee-script (~> 2.2)
+      coffee-script-source (~> 1.11.1)
+    jekyll-commonmark (1.2.0)
+      commonmarker (~> 0.14)
+      jekyll (>= 3.0, < 4.0)
+    jekyll-commonmark-ghpages (0.1.5)
+      commonmarker (~> 0.17.6)
+      jekyll-commonmark (~> 1)
+      rouge (~> 2)
+    jekyll-default-layout (0.1.4)
+      jekyll (~> 3.0)
+    jekyll-feed (0.11.0)
+      jekyll (~> 3.3)
+    jekyll-gist (1.5.0)
+      octokit (~> 4.2)
+    jekyll-github-metadata (2.12.1)
+      jekyll (~> 3.4)
+      octokit (~> 4.0, != 4.4.0)
+    jekyll-mentions (1.4.1)
+      html-pipeline (~> 2.3)
+      jekyll (~> 3.0)
+    jekyll-optional-front-matter (0.3.0)
+      jekyll (~> 3.0)
+    jekyll-paginate (1.1.0)
+    jekyll-readme-index (0.2.0)
+      jekyll (~> 3.0)
+    jekyll-redirect-from (0.14.0)
+      jekyll (~> 3.3)
+    jekyll-relative-links (0.6.0)
+      jekyll (~> 3.3)
+    jekyll-remote-theme (0.3.1)
+      jekyll (~> 3.5)
+      rubyzip (>= 1.2.1, < 3.0)
+    jekyll-sass-converter (1.5.2)
+      sass (~> 3.4)
+    jekyll-seo-tag (2.5.0)
+      jekyll (~> 3.3)
+    jekyll-sitemap (1.2.0)
+      jekyll (~> 3.3)
+    jekyll-swiss (0.4.0)
+    jekyll-theme-architect (0.1.1)
+      jekyll (~> 3.5)
+      jekyll-seo-tag (~> 2.0)
+    jekyll-theme-cayman (0.1.1)
+      jekyll (~> 3.5)
+      jekyll-seo-tag (~> 2.0)
+    jekyll-theme-dinky (0.1.1)
+      jekyll (~> 3.5)
+      jekyll-seo-tag (~> 2.0)
+    jekyll-theme-hacker (0.1.1)
+      jekyll (~> 3.5)
+      jekyll-seo-tag (~> 2.0)
+    jekyll-theme-leap-day (0.1.1)
+      jekyll (~> 3.5)
+      jekyll-seo-tag (~> 2.0)
+    jekyll-theme-merlot (0.1.1)
+      jekyll (~> 3.5)
+      jekyll-seo-tag (~> 2.0)
+    jekyll-theme-midnight (0.1.1)
+      jekyll (~> 3.5)
+      jekyll-seo-tag (~> 2.0)
+    jekyll-theme-minimal (0.1.1)
+      jekyll (~> 3.5)
+      jekyll-seo-tag (~> 2.0)
+    jekyll-theme-modernist (0.1.1)
+      jekyll (~> 3.5)
+      jekyll-seo-tag (~> 2.0)
+    jekyll-theme-primer (0.5.3)
+      jekyll (~> 3.5)
+      jekyll-github-metadata (~> 2.9)
+      jekyll-seo-tag (~> 2.0)
+    jekyll-theme-slate (0.1.1)
+      jekyll (~> 3.5)
+      jekyll-seo-tag (~> 2.0)
+    jekyll-theme-tactile (0.1.1)
+      jekyll (~> 3.5)
+      jekyll-seo-tag (~> 2.0)
+    jekyll-theme-time-machine (0.1.1)
+      jekyll (~> 3.5)
+      jekyll-seo-tag (~> 2.0)
+    jekyll-titles-from-headings (0.5.1)
+      jekyll (~> 3.3)
+    jekyll-watch (2.1.2)
+      listen (~> 3.0)
+    jemoji (0.10.2)
+      gemoji (~> 3.0)
+      html-pipeline (~> 2.2)
+      jekyll (~> 3.0)
+    kramdown (1.17.0)
+    liquid (4.0.0)
+    listen (3.1.5)
+      rb-fsevent (~> 0.9, >= 0.9.4)
+      rb-inotify (~> 0.9, >= 0.9.7)
+      ruby_dep (~> 1.2)
+    mercenary (0.3.6)
+    mini_portile2 (2.4.0)
+    minima (2.5.0)
+      jekyll (~> 3.5)
+      jekyll-feed (~> 0.9)
+      jekyll-seo-tag (~> 2.1)
+    minitest (5.11.3)
+    multipart-post (2.0.0)
+    nokogiri (1.10.4)
+      mini_portile2 (~> 2.4.0)
+    octokit (4.13.0)
+      sawyer (~> 0.8.0, >= 0.5.3)
+    pathutil (0.16.2)
+      forwardable-extended (~> 2.6)
+    public_suffix (3.0.3)
+    rb-fsevent (0.10.3)
+    rb-inotify (0.10.0)
+      ffi (~> 1.0)
+    rouge (2.2.1)
+    ruby-enum (0.7.2)
+      i18n
+    ruby_dep (1.5.0)
+    rubyzip (1.2.2)
+    safe_yaml (1.0.5)
+    sass (3.7.3)
+      sass-listen (~> 4.0.0)
+    sass-listen (4.0.0)
+      rb-fsevent (~> 0.9, >= 0.9.4)
+      rb-inotify (~> 0.9, >= 0.9.7)
+    sawyer (0.8.1)
+      addressable (>= 2.3.5, < 2.6)
+      faraday (~> 0.8, < 1.0)
+    terminal-table (1.8.0)
+      unicode-display_width (~> 1.1, >= 1.1.1)
+    thread_safe (0.3.6)
+    typhoeus (1.3.1)
+      ethon (>= 0.9.0)
+    tzinfo (1.2.5)
+      thread_safe (~> 0.1)
+    unicode-display_width (1.5.0)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  github-pages!
+  jekyll!
+
+BUNDLED WITH
+   2.0.1