Update gitlab-workhorse versions in documentation

[ci skip]

doc/install/installation.md

@@ -355,7 +355,7 @@ GitLab Shell is an SSH access and repository management software developed speci
     cd /home/git
     sudo -u git -H git clone https://gitlab.com/gitlab-org/gitlab-workhorse.git
     cd gitlab-workhorse
-    sudo -u git -H git checkout 0.5.4
+    sudo -u git -H git checkout 0.6.2
     sudo -u git -H make
 
 ### Initialize Database and Activate Advanced Features

doc/update/8.3-to-8.4.md

@@ -48,7 +48,7 @@ which should already be on your system from GitLab 8.1.
 ```bash
 cd /home/git/gitlab-workhorse
 sudo -u git -H git fetch --all
-sudo -u git -H git checkout 0.6.1
+sudo -u git -H git checkout 0.6.2
 sudo -u git -H make
 ```