Mention required Ruby version

doc/install/installation.md

@@ -107,9 +107,16 @@ Then select 'Internet Site' and press enter to confirm the hostname.
 
 ## 2. Ruby
 
-The use of Ruby version managers such as [RVM](https://rvm.io/), [rbenv](https://github.com/sstephenson/rbenv) or [chruby](https://github.com/postmodern/chruby) with GitLab in production frequently leads to hard to diagnose problems. For example, GitLab Shell is called from OpenSSH and having a version manager can prevent pushing and pulling over SSH. Version managers are not supported and we strongly advise everyone to follow the instructions below to use a system Ruby.
+_**Note:** The current supported Ruby versions are 2.1.x. Ruby 2.2 and 2.3 are
+currently not supported._
 
-Remove the old Ruby 1.8 if present
+The use of Ruby version managers such as [RVM], [rbenv] or [chruby] with GitLab
+in production, frequently leads to hard to diagnose problems. For example,
+GitLab Shell is called from OpenSSH, and having a version manager can prevent
+pushing and pulling over SSH. Version managers are not supported and we strongly
+advise everyone to follow the instructions below to use a system Ruby.
+
+Remove the old Ruby 1.8 if present:
 
     sudo apt-get remove ruby1.8
 
@@ -555,3 +562,7 @@ this is likely due to an outdated Nginx or Apache configuration, or a missing or
 misconfigured gitlab-workhorse instance. Double-check that you've
 [installed Go](#3-go), [installed gitlab-workhorse](#install-gitlab-workhorse),
 and correctly [configured Nginx](#site-configuration).
+
+[RVM]: https://rvm.io/ "RVM Homepage"
+[rbenv]: https://github.com/sstephenson/rbenv "rbenv on GitHub"
+[chruby]: https://github.com/postmodern/chruby "chruby on GitHub"

doc/install/requirements.md

@@ -32,15 +32,18 @@ Please consider using a virtual machine to run GitLab.
 
 ## Ruby versions
 
-GitLab requires Ruby (MRI) 2.1
+GitLab requires Ruby (MRI) 2.1.x and currently does not work with versions 2.2
+and 2.3.
+
 You will have to use the standard MRI implementation of Ruby.
-We love [JRuby](http://jruby.org/) and [Rubinius](http://rubini.us/) but GitLab needs several Gems that have native extensions.
+We love [JRuby](http://jruby.org/) and [Rubinius](http://rubini.us/) but GitLab
+needs several Gems that have native extensions.
 
 ## Hardware requirements
 
 ### Storage
 
-The necessary hard drive space largely depends on the size of the repos you want to store in GitLab but as a *rule of thumb* you should have at least as much free space as all your repos combined take up. 
+The necessary hard drive space largely depends on the size of the repos you want to store in GitLab but as a *rule of thumb* you should have at least as much free space as all your repos combined take up.
 
 If you want to be flexible about growing your hard drive space in the future consider mounting it using LVM so you can add more hard drives when you need them.
 
@@ -109,4 +112,4 @@ On a very active server (10,000 active users) the Sidekiq process can use 1GB+ o
 - Firefox (Latest released version and [latest ESR version](https://www.mozilla.org/en-US/firefox/organizations/))
 - Safari 7+ (known problem: required fields in html5 do not work)
 - Opera (Latest released version)
-- Internet Explorer (IE) 10+ but please make sure that you have the `Compatibility View` mode disabled.
\ No newline at end of file
+- Internet Explorer (IE) 10+ but please make sure that you have the `Compatibility View` mode disabled.