Restore: .gitignore changes for 22294af

git-svn-id: https://develop.svn.wordpress.org/branches/fixes-64393-restore-version-history@62117 602fd350-edb4-49c9-b593-d223f7449a82

Author: dmsnell

.gitignore

@@ -20,6 +20,7 @@ wp-tests-config.php
 /node_modules
 /npm-debug.log
 /build
+/gutenberg
 /tests/phpunit/build
 /wp-cli.local.yml
 /jsdoc