feat(index.html): add safeguards to the reload delay value

If the page reload value is not within specific range it will be
adjusted to a default of 10 seconds.

index.html

                     }
 
                     var delay = Math.pow(2, retryCount) * 2000;
+                    if (isNaN(delay) || delay < 2000 || delay > 60000)
+                        delay = 10000;
 
                     document.body.innerHTML
                         = "<div style='"