Added Must Use Plugins to gotignore (github#2553)

mostafasoufi · shiftkey · commit 1a9f616ce525 · 2017-12-21T09:00:58.000+10:30
https://codex.wordpress.org/Must_Use_Plugins
diff --git a/WordPress.gitignore b/WordPress.gitignore
@@ -7,6 +7,7 @@ wp-content/blogs.dir/
 wp-content/cache/
 wp-content/upgrade/
 wp-content/uploads/
+wp-content/mu-plugins/
 wp-content/wp-cache-config.php
 wp-content/plugins/hello.php
 
