Change logo link to point to the dashboard.

Signed-off-by: XhmikosR <xhmikosr@gmail.com>

scripts/pi-hole/php/header.php

@@ -257,7 +257,7 @@ if($auth) {
 <div class="wrapper">
     <header class="main-header">
         <!-- Logo -->
-        <a href="https://pi-hole.net/" class="logo" rel="noopener" target="_blank">
+        <a href="index.php" class="logo">
             <!-- mini logo for sidebar mini 50x50 pixels -->
             <span class="logo-mini">P<b>h</b></span>
             <!-- logo for regular state and mobile devices -->