add repository field to extensions package.json

extensions/perl/package.json

@@ -58,5 +58,9 @@
         "path": "./syntaxes/perl6.tmLanguage.json"
       }
     ]
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/microsoft/vscode.git"
   }
 }