Merge branch 'dev-rake-task-docs' into 'master'

Dev rake task docs

As discussed in #1184

See merge request !1301

doc/development/rake_tasks.md

 # Rake tasks for developers
 
-## Setup db with developer seeds:
+## Setup db with developer seeds
 
 Note that if your db user does not have advanced privileges you must create the db manually before running this command.
 
@@ -8,6 +8,10 @@ Note that if your db user does not have advanced privileges you must create the
 bundle exec rake setup
 ```
 
+The `setup` task is a alias for `gitlab:setup`.
+This tasks calls `db:setup` to create the database, calls `add_limits_mysql` that adds limits to the database schema in case of a MySQL database and fianlly it calls `db:seed_fu` to seed the database.
+Note: `db:setup` calls `db:seed` but this does nothing.
+
 ## Run tests
 
 This runs all test suites present in GitLab.