Add function to post to create milestone

Author: sajidanower23

src/GitHub/Endpoints/Issues/Milestones.hs

@@ -51,3 +51,13 @@ milestone user repo mid =
 milestoneR :: Name Owner -> Name Repo -> Id Milestone -> Request k Milestone
 milestoneR user repo mid =
     query ["repos", toPathPart user, toPathPart repo, "milestones", toPathPart mid] []
+
+createMilestone :: Auth -> Name Owner -> Name Repo -> NewMilestone -> IO (Either Error Milestone)
+createMilestone auth user repo mst = executeRequest auth $ createMilestoneR user repo mst
+
+-- | Create a milestone.
+-- See <https://developer.github.com/v3/issues/milestones/#create-a-milestone>
+createMilestoneR :: Name Owner -> Name Repo -> NewMilestone -> Request 'RW Milestone
+createMilestoneR user repo =
+    command Post ["repos", toPathPart user, toPathPart repo, "milestones"] . encode
+