Fix the link to the GitLab Enterprise Edition

which was moved from 'gitlab-org/gitlab-ee' to 'gitlab-org/gitlab'. 

doc/install/installation.md

@@ -462,7 +462,7 @@ Clone Enterprise Edition:
 
 ```shell
 # Clone GitLab repository
-sudo -u git -H git clone https://gitlab.com/gitlab-org/gitlab-ee.git -b X-Y-stable gitlab
+sudo -u git -H git clone https://gitlab.com/gitlab-org/gitlab.git -b X-Y-stable gitlab
 ```
 
 Make sure to replace `X-Y-stable` with the stable branch that matches the