provide registration reason in register approve email

src/Lib/Account.php

@@ -380,6 +380,7 @@ class Account {
                 '$sitename' => get_config('system', 'sitename'),
                 '$siteurl'  =>  z_root(),
                 '$email'    => $arr['email'],
+                '$reason'   => $arr['reason'],
                 '$uid'      => $arr['account']['account_id'],
                 '$hash'     => $hash,
                 '$details'  => $details

src/Module/Register.php

@@ -181,6 +181,7 @@ class Register extends Controller
                 }
             }
         } elseif ($policy == REGISTER_APPROVE) {
+            $result['reason'] = substr(trim(escape_tags($_REQUEST['reason'])),0, 500);
             $res = Account::send_reg_approval_email($result);
             if ($res) {
                 info(t('Your registration is pending approval by the site owner.') . EOL);

view/en/register_verify_eml.tpl

@@ -2,6 +2,8 @@
 A new user registration request was received at {{$sitename}} which requires 
 your approval. 
 
+Reason:
+{{$reason}}
 
 The login details are as follows: