Correct spelling mistake.

config/gitlab.yml.example

@@ -56,7 +56,7 @@ production: &base
     # signup_enabled: true
 
     ## Automatic issue closing
-    # If a commit message matches this regular express, all issues referenced from the matched text will be closed.
+    # If a commit message matches this regular expression, all issues referenced from the matched text will be closed.
     # This  happends when the commit is pushed or merged into the default branch of a project.
     # When not specified the default issue_closing_pattern as specified below will be used.
     # issue_closing_pattern: ([Cc]loses|[Ff]ixes) +#\d+