MDL-31107 Fixing instaces of below where it is written as bellow (two L's)

lib/htmlpurifier/HTMLPurifier/Lexer/PH5P.php

@@ -1113,7 +1113,7 @@ class HTML5 {
                 $entity = $this->character($start, $this->char);
                 $cond = strlen($e_name) > 0;
 
-                // The rest of the parsing happens bellow.
+                // The rest of the parsing happens below.
             break;
 
             // Anything else
@@ -1140,7 +1140,7 @@ class HTML5 {
                 }
 
                 $cond = isset($entity);
-                // The rest of the parsing happens bellow.
+                // The rest of the parsing happens below.
             break;
         }