[docs] Fix the milestone filetring doc (iid -> iids)

Gauvain Pocentek · Gauvain Pocentek · commit 0c9a00bb1540 · 2018-11-22T18:17:37.000+01:00
Fixes python-gitlab#633
diff --git a/docs/gl_objects/milestones.rst b/docs/gl_objects/milestones.rst
@@ -30,7 +30,7 @@ List the milestones for a project or a group::
 
 You can filter the list using the following parameters:
 
-* ``iid``: unique ID of the milestone for the project
+* ``iids``: unique IDs of milestones for the project
 * ``state``: either ``active`` or ``closed``
 * ``search``: to search using a string
 
