Update disallow-edits.yml

Author: gewarren

.github/policies/disallow-edits.yml

@@ -10,6 +10,8 @@ configuration:
           - payloadType: Pull_Request
           - isAction:
               action: Opened
+          - targetsBranch:
+              branch: main
           - or:
               - filesMatchPattern:
                   pattern: xml/Microsoft.Extensions*/*