Update pull request documentation

documentation/markdown/prezto.md

@@ -73,6 +73,43 @@ Resources
 
 The [Zsh Reference Card][7] and the [zsh-lovers][8] man page are indispensable.
 
+Contribute
+----------
+
+This project would not exist without all of its users and [contributors][9].
+
+If you have ideas on how to make the configuration easier to maintain or
+improve its performance, do not hesitate to fork and send pull requests.
+
+### Issue Reporting
+
+   - Check that the issue has not already been reported.
+   - Check that the issue has not already been fixed in the latest code.
+   - Open an issue with a clear title and description in grammatically correct,
+     complete sentences.
+
+### Pull Request
+
+   - Read [how to properly contribute to open source projects on GitHub][10].
+   - Use a topic branch to easily amend a pull request later, if necessary.
+   - Write [good commit messages][11].
+   - Squash commits on the topic branch before opening a pull request.
+   - Use the same coding style and spacing.
+   - Open a [pull request][12] that relates to but one subject with a clear
+     title and description in grammatically correct, complete sentences.
+
+#### Modules
+
+   - Markdown and man page documentation must be present.
+   - Large functions must be placed in a *functions* directory.
+   - Functions that take arguments must have completion.
+
+#### Themes
+
+   - A screenshots section must be present in the file header.
+   - The pull request description must have [embedded
+     screenshots][13].
+
 License
 -------
 
@@ -106,4 +143,9 @@ SOFTWARE.
 [6]: http://gitref.org
 [7]: http://www.bash2zsh.com/zsh_refcard/refcard.pdf
 [8]: http://grml.org/zsh/zsh-lovers.html
+[9]: https://github.com/sorin-ionescu/prezto/contributors
+[10]: http://gun.io/blog/how-to-github-fork-branch-and-pull-request
+[11]: http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html
+[12]: https://help.github.com/articles/using-pull-requests
+[13]: http://daringfireball.net/projects/markdown/syntax#img