Adding config for reusable content repo

Author: buck1ey

.openpublishing.publish.config.json

@@ -63,6 +63,12 @@
       "url": "https://github.com/microsoft/PowerApps-Samples",
       "branch": "master",
       "branch_mapping": {}
+    },
+    {
+      "path_to_root": "msft-shared-content",
+      "url": "https://github.com/MicrosoftDocs/reusable-content",
+      "branch": "main",
+      "branch_mapping": {}
     }
   ],
   "branch_target_mapping": {
@@ -92,4 +98,4 @@
   "docs_build_engine": {
     "name": "docfx_v3"
   }
-}
+}