fixed win_feature docs

added version_added for source and fixed some yaml parsing

lib/ansible/modules/windows/win_feature.py

@@ -68,8 +68,9 @@ options:
       - Specify a source to install the feature from
     required: false
     choices:
-      - {driveletter}:\sources\sxs
-      - \\{IP}\Share\sources\sxs
+      - "{driveletter}:\sources\sxs"
+      - "{IP}\Share\sources\sxs"
+    version_added: "2.1"
 author:
     - "Paul Durivage (@angstwad)"
     - "Trond Hindenes (@trondhindenes)"