Merge branch 'git-hooks-docs' into 'master'

Add documentation for EE Git Hooks feature

Fixes #99

doc/README.md

@@ -19,9 +19,10 @@
 - [Security](security/README.md) Learn what you can do to further secure your GitLab instance.
 - [Update](update/README.md) Update guides to upgrade your installation.
 - [Branded login page](customization/branded_login_page.md) Change the login page appearance for your GitLab instance.
+- [Git Hooks](git_hooks/git_hooks.md) Advanced push rules for your project.
 
 ## Contributor documentation
 
 - [Development](development/README.md) Explains the architecture and the guidelines for shell commands.
 - [Legal](legal/README.md) Contributor license agreements.
-- [Release](release/README.md) How to make the monthly and security releases.
+- [Release](release/README.md) How to make the monthly and security releases.
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doc/git_hooks/git_hooks.md

+# Git Hooks
+
+Sometimes you need additional control over pushes to your repository. 
+GitLab already offers protected branches. 
+But there are cases when you need some specific rules like preventing git tag removal or enforcing a special format for commit messages. 
+GitLab Enterprise Edition offers a user-friendly interface for such cases.
+
+Git hooks are defined per project so you can have different rules applied to different projects depends on your needs. 
+Git hooks settings can be found at Project settings -> Git Hooks page. 
+
+
+## How to use
+
+Let's assume you have the following requirements for your workflow:
+
+* every commit should reference a reference JIRA issue. For example: `Refactored css. Fixes JIRA-123. `
+* users should not be able to remove git tags with `git push`
+
+All you need to do is write simple regular expression that requires mention of JIRA issue in a commit message. 
+It can be something like this `/JIRA\-\d+/`. 
+Just paste regular expression into commit message textfield(without start and ending slash) and save changes. 
+See the screenshot below: 
+
+![screenshot](git_hooks.png)
+
+Now when a user tries to push a commit like `Bugfix` - their push will be declined. 
+And pushing commit with message like `Bugfix according to JIRA-123` will be accepted.
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