Add note to enable caching in prod

Author: pierredup

symfony/webpack-encore-bundle/1.0/config/packages/webpack_encore.yaml

@@ -8,6 +8,7 @@ webpack_encore:
     # if using Encore.enableIntegrityHashes() specify the crossorigin attribute value (default: false, or use 'anonymous' or 'use-credentials')
     # crossorigin: 'anonymous'
 
-    # Cache the entrypoints.json (rebuild Symfony's cache when entrypoints.json changes)
+    # Cache the entrypoints.json (rebuild Symfony's cache when entrypoints.json changes).
+    # To enable caching for the production environment, creating a webpack_encore.yaml in the config/packages/prod directory with this value set to true
     # Available in version 1.2
     #cache: 'false'