MNT: Lint markdown files

.github/issue_template.md

@@ -3,6 +3,7 @@ NOTE: Only submit issues for Python package "pdoc3" on PyPI.
Python package "pdoc" lives elsewhere.
-->


### Expected Behavior

.github/lint-markdown.sh

@@ -0,0 +1,16 @@
#!/bin/bash
set -eu

error () { echo "ERROR in '$file': $@" >&2; exit 1; }

for file in "$@"; do
    if grep '\x0D' "$file"; then
        error 'Use LF to end lines, not CRLF'
    fi
    if grep -Pzo '(?<![-=\n]\n\n)(?<=\n)(#+ \N*\w\N*|\N*\w\N*\n-+)\n' "$file"; then
        error 'Need two blank lines before heading'
    fi
    if grep -Pv '^(\[[^\]]+\]: .*|\[!.*\))$' "$file" | grep -Pvn '^.{0,90}$'; then
        error 'Lines too long'
    fi
done

.travis.yml

@@ -19,6 +19,7 @@ matrix:
      before_script:
        - pip install flake8 coverage mypy
      script:
        - find -name '*.md' | xargs .github/lint-markdown.sh
        - flake8
        - mypy pdoc
        - time catchsegv coverage run setup.py test