Fix env variable name

Fixed env variable name which points to host source directory.

docker-sync.yml

@@ -6,7 +6,7 @@ syncs:
   applications-docker-sync: # name of the intermediary sync volume
     compose-dev-file-path: 'docker-compose.sync.yml' # docker-compose override file
 
-    src: '${APPLICATION}' # host source directory
+    src: '${APP_CODE_PATH_HOST}' # host source directory
     sync_userid: 1000 # giving permissions to www-data user (as defined in nginx and php-fpm Dockerfiles)
     sync_strategy: '${DOCKER_SYNC_STRATEGY}' # for osx use 'native_osx', for windows use 'unison'