Add link to repo

Author: FedericoPonzi

web/index.html

@@ -166,6 +166,7 @@
 
 <header>
     <h1>TLA+ Formatter</h1>
+    <a href="https://github.com/FedericoPonzi/tlaplus-formatter" target="_blank" rel="noopener noreferrer" style="color: #eee; text-decoration: none; font-size: 0.9rem;">GitHub</a>
     <div class="controls">
         <label>
             Width