Split Contributing section to its own document.

CONTRIBUTING.md

@@ -0,0 +1,53 @@
+# Contributing
+
+The release of Bootstrap 4 and Rails 5.1 have implications
+for the future direction of `bootstrap_form`.
+Don't worry.
+We plan to move this gem forward to Bootstrap 4
+and to support Rails 5.1 and beyond.
+If you're thinking of contributing to `bootstrap_form`,
+please read [issue #361](https://github.com/bootstrap-ruby/rails-bootstrap-forms/issues/361).
+Your comments are welcome.
+
+Thanks so much for considering contributing to bootstrap_form!
+We love pull requests!
+
+Here's a quick guide for contributing:
+
+1. Make sure no one else is working on the same issue or feature.
+Search the issues and pull requests for anything
+that looks like the issue or feature you want to address.
+If no one else is working on your issue or feature,
+carry on with the following steps.
+
+2. Fork the repo.
+
+2. Install the required dependencies.
+
+```
+bundle install
+bundle exec appraisal install
+```
+
+3. Run the existing test suite:
+
+```
+$ bundle exec rake -f test/dummy/Rakefile db:create db:migrate RAILS_ENV=test
+$ bundle exec appraisal rake test
+```
+
+4. Add tests for your change.
+
+5. Add your changes and make your test(s) pass. Following the conventions you
+see used in the source will increase the chance that your pull request is
+accepted right away.
+
+6. Update the README if necessary.
+
+7. Add a line to the CHANGELOG for your bug fix or feature.
+
+8. Push to your fork and submit a pull request.
+
+## Contributors
+
+Thanks to all the great contributors over the years: https://github.com/bootstrap-ruby/rails-bootstrap-forms/graphs/contributors

README.md

@@ -582,39 +582,10 @@ http://www.codetriage.com/potenza/bootstrap_form
 
 ## Contributing
 
-We love pull requests! Here's a quick guide for contributing:
-
-1. Fork the repo.
-
-2. Install the required dependencies.
-
-```
-bundle install
-bundle exec appraisal install
-```
-
-3. Run the existing test suite:
-
-```
-$ bundle exec rake -f test/dummy/Rakefile db:create db:migrate RAILS_ENV=test
-$ bundle exec appraisal rake test
-```
-
-4. Add tests for your change.
-
-5. Add your changes and make your test(s) pass. Following the conventions you
-see used in the source will increase the chance that your pull request is
-accepted right away.
-
-6. Update the README if necessary.
-
-7. Add a line to the CHANGELOG for your bug fix or feature.
-
-8. Push to your fork and submit a pull request.
-
-## Contributors
-
-https://github.com/bootstrap-ruby/rails-bootstrap-forms/graphs/contributors
+We welcome contributions.
+If you're considering contributing to bootstrap_form,
+please review the [Contributing](/CONTRIBUTING.md)
+document first.
 
 ## License