Update installation.md - Updated the Ruby section.
Updated the Ruby section.
Fixes my previous my old obsolete/forgotten pull request / patch (sorry about that): #6262 https://github.com/lpalgarvio/gitlabhq/tree/patch-1
Updated the Ruby section.
Fixes my previous my old obsolete/forgotten pull request / patch (sorry about that): #6262 https://github.com/lpalgarvio/gitlabhq/tree/patch-1