fixup! fixup! Link to the contributing guide in the docs

CONTRIBUTING.md

@@ -12,12 +12,13 @@ project codebases, issue trackers, chat-rooms, and mailing lists.
 
 ## Getting Started
 
-Administrate is a Rails Engine, but ships with everything needed to contribute 
-and test new changes.
+Administrate is a [Rails Engine][], but ships with everything needed to
+contribute and test new changes.
 
 To maintain compatibility with multiple dependency versions, we use
 [Appraisal][].
 
+[Rails Engine]: https://guides.rubyonrails.org/engines.html
 [Appraisal]: https://github.com/thoughtbot/appraisal
 
 ### Opening a PR
@@ -29,6 +30,9 @@ To maintain compatibility with multiple dependency versions, we use
 4. Make your changes,
 5. Push your fork and open a pull request.
 
+A good PR will solve the smallest problem it possibly can, have good test
+coverage and (where necessary) have internationalisation support.
+
 ### Running the application locally
 
 Administrate's demo application can be run like any Rails application:
@@ -41,14 +45,10 @@ This will start the application defined in `spec/example_app`.
 
 ## Repository Structure
 
-This repository contains both the source code for Administrate,
-and a demo Rails app that uses Administrate.
-The demo app is [hosted publicly on Heroku][demo].
-
-- The gem's source code lives in the `app` and `lib` subdirectories.
-- The demo app is nested within `spec/example_app`.
-- The guides as seen at
-  [https://administrate-prototype.herokuapp.com][prototype_heroku] live as
+* The gem's source code lives in the `app` and `lib` subdirectories.
+* The demo app is nested within `spec/example_app`.
+* The guides as seen at
+  [https://administrate-demo.herokuapp.com][docs] live as
   markdown files in the `docs` subdirectory.
 
 Rails configuration files have been changed
@@ -57,19 +57,22 @@ so running the server or deploying to Heroku works normally.
 
 With this structure, developing a typical feature looks like:
 
-- Add tests in `spec/`
-- Implement a feature in `administrate/`
-- Exercise the feature using the demo rails app (`spec/example_app/app/`)
+* Add tests in `spec/`
+* Implement a feature in `administrate/`
+* Exercise the feature using the demo rails app (`spec/example_app/app/`)
+
+[demo]: https://administrate-prototype.herokuapp.com/admin
+[docs]: https://administrate-prototype.herokuapp.com
 
 ## Front-end Architecture
 
 This project uses:
 
-- Sass
-- [BEM]-style CSS selectors, with [namespaces]
-- Autoprefixer
-- SCSS-Lint, with [Hound] ([configuration](.scss-lint.yml))
-- A variety of CSS units:
+* Sass
+* [BEM]-style CSS selectors, with [namespaces]
+* Autoprefixer
+* SCSS-Lint, with [Hound] ([configuration](.scss-lint.yml))
+* A variety of CSS units:
   - `em` for typographical-related elements
   - `rem` for lengths related to components
   - `px` for borders, text shadows, etc.