add contributing file

CONTRIBUTING.md

@@ -0,0 +1,40 @@
+The `lobsters` codebase is under a [3-clause BSD
+license](https://github.com/jcs/lobsters/blob/master/LICENSE).  All code
+submitted must be licensed under these or more-permissive terms (2-clause BSD,
+MIT, ISC, etc.).
+
+### Making Changes
+
+Not all changes or new features submitted will be accepted.  Please discuss
+your proposed changes on [/t/meta](https://lobste.rs/t/meta) or as a
+[Github issue](https://github.com/jcs/lobsters/issues) before working on them
+to avoid wasted efforts.
+
+* Fork [jcs/lobsters](https://github.com/jcs/lobsters) on Github.
+
+* (Optional) Create a branch to house your changes.
+
+* Wrap code at 80 characters with 2-space soft tabs for Ruby code.  For other
+languages, use the existing style of the files being edited.  3rd party,
+externally-maintained code such as Javascript libraries can remain in their
+own style.
+
+* Check for unnecessary whitespace with `git diff --check` before committing.
+Commit whitespace and other code cleanups separately so that your actual
+changes can be easily understood.
+
+* Write a proper commit message with the first line being a short,
+present-tense explanation of the change.  Wrap all lines at 80 characters.
+
+* If applicable, add tests for your changes.  Not all changes require tests,
+and tests should not be added just for the sake of code coverage.
+
+* Run _all_ tests (with `rake` in the root directory) to ensure nothing has
+been broken by your changes.
+
+### Submitting Changes
+
+* Push your changes to your fork of the repository (to your branch if you
+created one).
+
+* Submit a pull request to [jcs/lobsters](https://github.com/jcs/lobsters).

README.md

@@ -71,3 +71,8 @@ You should define this in `/etc/hosts` (or through DNS) to point to
 `http://lobsters.localhost:3000` with your `test` user:
 
           lobsters$ rails server
+
+####Contributing bugfixes and new features
+
+Please see the [CONTRIBUTING](https://github.com/jcs/lobsters/blob/master/CONTRIBUTING.md)
+file.