Add = in front of a keyword highlighter

Author: gg582

src/languages/systemd.js

@@ -9,7 +9,7 @@ Website: https://www.freedesktop.org/
 export default function(hljs) {
   const LITERALS = {
     className: 'literal',
-    begin: /\b(true|false|Application|Link|Directory|forking|oneshot|OneShot)\b/,
+    begin: /=\b(true|false|Application|Link|Directory|forking|oneshot|OneShot)\b/,
     relevance: 0
   };