chore: tidy up index.html

Author: xhwang-chromium

encrypted-media-respec.html

@@ -3124,7 +3124,7 @@ <h2>
               Some key systems also support requesting the certificate from the server via the
               [=Queue a "message" Event=] algorithm. However, this is not supported by all key
               systems that use such certificates.
-            </p>          
+            </p>
             <p>
               The server certificate contents are [=Key System=]-specific. It MUST NOT contain
               executable code.