Add docs for Ruby

docs/app/docs/language_support/ruby.md

@@ -0,0 +1,50 @@
+---
+title: Ruby
+---
+
+### Detection
+
+Devbox will automatically create a Ruby project plan whenever a `Gemfile` file is detected in the project's root directory.
+
+### Supported Versions
+
+Devbox will attempt to install the Ruby version specified in the `Gemfile`, but it is limited to the following versions: `3.1.2`, `3.0.4`, and `2.7.6`.
+
+### Included Nix Packages
+
+Install and Build Stage Image:
+* Ruby (either `ruby_3_1`, `ruby_3_0`, or `ruby`)
+* `gcc`
+* `gnumake`
+
+GCC and Make are included in case certain gems require them, like `rails`.
+
+Start Stage Image:
+* Ruby (either `ruby_3_1`, `ruby_3_0`, or `ruby`)
+
+### Default Stages
+These stages can be customized by adding them to your `devbox.json`. See the [Configuration Guide](../configuration.md) for more details.
+
+#### Install Stage
+
+```bash
+bundle config set --local deployment 'true' && bundle install
+```
+
+#### Build Stage
+
+Skipped: _This stage is skipped for Ruby projects_
+
+#### Start Stage
+
+If `rails` is detected in the `Gemfile`, then:
+```bash
+./bin/rails server -b 0.0.0.0 -e production
+```
+
+You can then `docker run -p 3000:3000 devbox` and access your project at `0.0.0.0:3000`.
+
+Else (not a Rails project):
+```bash
+bundle exec ruby app.rb
+```

docs/app/sidebars.js

@@ -93,6 +93,9 @@ const sidebars = {
             id: 'language_support/python'
         }, {
             type: 'doc',
+            id: 'language_support/ruby'
+        }, {
+           type: 'doc',
             id: 'language_support/rust'
         }, {
             type: 'doc',