Add explicit example of how to test the Promise status

Author: zoffixznet

doc/Type/Promise.pod6

@@ -208,7 +208,9 @@ C<Planned>.
 
     method status(Promise:D) returns PromiseStatus
 
-Returns the current state of the promise: C<Kept>, C<Broken> or C<Planned>.
+Returns the current state of the promise: C<Kept>, C<Broken> or C<Planned>:
+
+    say "promise got Kept" if $promise.status ~~ Kept;
 
 =head2 method scheduler