Fix typo in admin_settings_quote.php

Fixed typo in placeholder for email address to notify when quotes are accepted/declined.

... leave bank for none -> ...leave blank for none.

admin_settings_quote.php

@@ -41,7 +41,7 @@
                         <div class="input-group-prepend">
                             <span class="input-group-text"><i class="fa fa-fw fa-bell"></i></span>
                         </div>
-                        <input type="email" class="form-control" name="config_quote_notification_email" placeholder="Address to notify for quote accept/declines, leave bank for none" value="<?php echo nullable_htmlentities($config_quote_notification_email); ?>">
+                        <input type="email" class="form-control" name="config_quote_notification_email" placeholder="Address to notify for quote accept/declines, leave blank for none" value="<?php echo nullable_htmlentities($config_quote_notification_email); ?>">
                     </div>
                 </div>