Merge pull request #684 from ilpianista/bugfix/gitlab_project_membership-docs

Fix GitLab project membership example

Author: Julien Pivotto

docs/resources/project_membership.md

@@ -30,7 +30,7 @@ The following arguments are supported:
 
 ## Import
 
-GitLab group membership can be imported using an id made up of `group_id:user_id`, e.g.
+GitLab project membership can be imported using an id made up of `project_id:user_id`, e.g.
 
 ```
 $ terraform import gitlab_project_membership.test "12345:1337"