Update frontpage message.

Author: root

codalab/apps/web/templates/web/index.html

@@ -25,7 +25,7 @@
                 <div style="margin-top: 15px;" class="well">
                     <p>Dear Codalab users,</p>
                     <p style='color:red'><b>
-                        The platform is currently short on storage. Please use as little storage as possible.
+                        A maintenance operation is planned on the 23rd of July 2021. Thank you for your comprehension.
                     </b></p>
                     <p style='color:blue'><b>
                         To help build our community we created this