docs(CONTRIBUTING.md): add note about scope wildcard

jsoref · petebacondarwin · commit bdf960294ada · 2016-11-01T10:32:03.000Z
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
@@ -249,6 +249,8 @@ Must be one of the following:
 The scope could be anything specifying place of the commit change. For example `$location`,
 `$browser`, `$compile`, `$rootScope`, `ngHref`, `ngClick`, `ngView`, etc...
 
+You can use `*` when the change affects more than a single scope.
+
 ### Subject
 The subject contains succinct description of the change:
 
