Update CONTRIBUTING.md

Author: Antonboom

CONTRIBUTING.md

@@ -46,7 +46,7 @@ the rest of the checkers will become irrelevant.
 ```go
 var registry = checkersRegistry{
     // ...
-    {factory: asCheckerFactory(NewTimeCompare), enabledByDefault: false},
+    {factory: asCheckerFactory(NewTimeCompare), enabledByDefault: true},
     // ...
     {factory: asCheckerFactory(NewEmpty), enabledByDefault: true},
     // ...