Update select branch to GitLab look and explain why this guide is long so...

Update select branch to GitLab look and explain why this guide is long so people are not discouraged.

doc/install/installation.md

@@ -2,12 +2,14 @@
 Make sure you view this installation guide from the branch (version) of GitLab you would like to install. In most cases
 this should be the highest numbered stable branch (example shown below).
-![capture](https://f.cloud.github.com/assets/1192780/564911/2f9f3e1e-c5b7-11e2-9f89-98e527d1adec.png)
+![capture](http://i.imgur.com/d2AlIVj.png)
 If this is unclear check the [GitLab Blog](http://blog.gitlab.org/) for installation guide links by version.
 # Important notes
+This guide is long because it covers many cases and includes all commands you need, this is [one of the few installation scripts that actually works out of the box](https://twitter.com/robinvdvleuten/status/424163226532986880).
+
 This installation guide was created for and tested on **Debian/Ubuntu** operating systems. Please read [`doc/install/requirements.md`](./requirements.md) for hardware and operating system requirements.
 This is the official installation guide to set up a production server. To set up a **development installation** or for many other installation options please consult [the installation section in the readme](https://github.com/gitlabhq/gitlabhq#installation).