Public contributions point to master branch

Author: mattwojo

.openpublishing.publish.config.json

@@ -19,6 +19,8 @@
   ],
   "notification_subscribers": [],
   "branches_to_filter": [],
+  "git_repository_url_open_to_public_contributors": "https://github.com/MicrosoftDocs/wsl",
+  "git_repository_branch_open_to_public_contributors": "master",
   "skip_source_output_uploading": false,
   "contribution_branch_mappings": {},
   "dependent_repositories": [