Link to installation guide.

README.md

-# GitLab CI is an open-source continuous integration server 
+# GitLab CI is an open-source continuous integration server
 [![build status](https://secure.travis-ci.org/gitlabhq/gitlab-ci.png)](https://travis-ci.org/gitlabhq/gitlab-ci) [![Code Climate](https://codeclimate.com/badge.png)](https://codeclimate.com/github/gitlabhq/gitlab-ci)
 ![Screen](https://github.com/downloads/gitlabhq/gitlab-ci/gitlab_ci_preview.png)
-
-# Requirements: 
+### Requirements
 **The project is designed for the Linux operating system.**
@@ -15,5 +14,6 @@ We officially support (recent versions of) these Linux distributions:
 __We recommend to use server with at least 756MB RAM for gitlab-ci instance.__
-Check out doc/installation.md for setup instructions
+### Installation
+* [Installation and setup guide](https://github.com/gitlabhq/gitlab-ci/blob/master/doc/installation.md)