Correct spelling error

Author: jliljekrantz

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

@@ -34,7 +34,7 @@ image::images/gitlab-menu.png[The “Admin area” item in the GitLab menu]
 
 ===== Users
 
-Everybody using your GitLab server must have an user account.
+Everybody using your GitLab server must have a user account.
 User accounts are quite simple, they mainly contain personal information attached to login data.
 Each user account has a *namespace*, which is a logical grouping of projects that belong to that user.
 If the user +jane+ had a project named +project+, that project's url would be `http://server/jane/project`.