add button to list of elements that can be associated with a label

Author: huynhducduy

src/rules/label-has-associated-control.js

@@ -69,6 +69,7 @@ export default ({
         'progress',
         'select',
         'textarea',
+        'button',
       ].concat((options.controlComponents || []));
       // Prevent crazy recursion.
       const recursionDepth = Math.min(