Add link to git hooks doc from read me

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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