mkdocs: update 404 override

Author: practicalli-johnny

overrides/404.html

@@ -14,11 +14,11 @@ <h3>
 </h3>
 
 <p>
-    Practicalli Learn Clojure is actively being developed
+    Practicalli website are published using Material for MkDocs
 </p>
 
 <p>
-    Try use the Search bar at the top of the page
+    Use the Search bar at the top of the page or left navigation to find the relevant content.
 </p>
 
 <p>