Enable focus for z-index by default

Author: adamwathan

stubs/defaultConfig.stub.js

@@ -748,7 +748,7 @@ module.exports = {
     whitespace: ['responsive'],
     width: ['responsive'],
     wordBreak: ['responsive'],
-    zIndex: ['responsive'],
+    zIndex: ['responsive', 'focus'],
     gap: ['responsive'],
     gridAutoFlow: ['responsive'],
     gridTemplateColumns: ['responsive'],