correct casing for the 21no.de link in footer

Author: jkyberneees

docs/index.html

@@ -1406,7 +1406,7 @@ <h4>Community</h4>
             <ul>
               <li><a href="https://github.com/BackendStack21/kai/issues">Issues</a></li>
               <li><a href="https://github.com/BackendStack21/kai/discussions">Discussions</a></li>
-              <li><a href="https://21no.de">21NO.DE</a></li>
+              <li><a href="https://21no.de">21no.de</a></li>
             </ul>
           </div>
         </div>