Clarify whose fork/copy it is in the text

Author: HonkingGoose

book/04-git-server/sections/gitlab.asc

@@ -119,7 +119,7 @@ By giving a user an access level of ``Developer'' or above, that user can push c
 Another, more decoupled way of collaboration is by using merge requests.
 This feature enables any user that can see a project to contribute to it in a controlled way.
 Users with direct access can simply create a branch, push commits to it, and open a merge request from their branch back into `master` or any other branch.
-Users who don't have push permissions for a repository can ``fork'' it (create their own copy), push commits to _that_ copy, and open a merge request from their fork back to the main project.
+Users who don't have push permissions for a repository can ``fork'' it to create their own copy, push commits to _their_ copy, and open a merge request from their fork back to the main project.
 This model allows the owner to be in full control of what goes into the repository and when, while allowing contributions from untrusted users.
 
 Merge requests and issues are the main units of long-lived discussion in GitLab.