docs: use case sensitive javascript

Signed-off-by: Martin Kletzander <mkletzan@redhat.com>

docs/js/main.js

@@ -28,7 +28,7 @@ function pageload() {
     advancedSearch.className = "advancedsearch"
 
     simpleSearch = document.getElementById("simplesearch")
-    simplesearch.addEventListener("submit", advancedsearch)
+    simpleSearch.addEventListener("submit", advancedsearch)
 }
 
 function advancedsearch(e) {