Update docfx.json

Added sharepoint-pno ms.service value to squash build report errors

Author: chrisda

sharepoint/docfx.json

@@ -70,6 +70,9 @@
       },
       "ms.prod":{
         "sharepoint-ps/sharepoint-server/*.yml":"sharepoint-2016-powershell"
+      },
+      "ms.service":{
+        "sharepoint-ps/sharepoint-pnp/*.yml":"sharepoint-pnp"
       }
     },
     "template": [],