Update .openpublishing.publish.config.json

Author: sankethka

.openpublishing.publish.config.json

@@ -10,6 +10,7 @@
       "locale": "en-us",
       "monikers": [],
       "open_to_public_contributors": true,
+       "git_repository_branch_open_to_public_contributors": "master",
       "type_mapping": {
         "Conceptual": "Content",
         "ManagedReference": "Content",
@@ -119,4 +120,4 @@
   ],
   "need_generate_pdf_url_template": false,
   "dest": "_site"
-}
+}