Add rule to index.js

Author: Luke Zapart

index.js

@@ -70,6 +70,7 @@ const allRules = {
   'no-unused-state': require('./lib/rules/no-unused-state'),
   'no-will-update-set-state': require('./lib/rules/no-will-update-set-state'),
   'prefer-es6-class': require('./lib/rules/prefer-es6-class'),
+  'prefer-read-only-props': require('./lib/rules/prefer-read-only-props'),
   'prefer-stateless-function': require('./lib/rules/prefer-stateless-function'),
   'prop-types': require('./lib/rules/prop-types'),
   'react-in-jsx-scope': require('./lib/rules/react-in-jsx-scope'),