Use boolean instead of string.

Author: OskarStark

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

@@ -11,4 +11,4 @@ webpack_encore:
     # 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'
+    #cache: false