update with existing .openpublishing.publish.config.json (#160)

Co-authored-by: Ying Hua <[email protected]>

Author: BillWagner

.openpublishing.publish.config.json

@@ -36,15 +36,17 @@
     }
   ],
   "notification_subscribers": [],
+  "sync_notification_subscribers": null,
   "branches_to_filter": [],
   "skip_source_output_uploading": false,
   "need_preview_pull_request": true,
   "need_pr_comments": false,
+  "contribution_branch_mappings": null,
   "dependent_repositories": [
     {
       "path_to_root": "_themes",
       "url": "https://github.com/Microsoft/templates.docs.msft",
-      "branch": "master",
+      "branch": "main",
       "branch_mapping": {}
     },
     {
@@ -54,6 +56,7 @@
       "branch_mapping": {}
     }
   ],
+  "branch_target_mapping": null,
   "need_generate_pdf_url_template": false,
   "need_generate_pdf": false,
   "need_generate_intellisense": false,
@@ -86,4 +89,4 @@
   "docs_build_engine": {
     "name": "docfx_v3"
   }
-}
+}