Update for add forge now email template to forge admin

Change the subject and the body of the email sent to the forge admin when a new add forge now request is created, in order to avoid any confusion : the message is informative, it is not a demand of approval to the forge admin.

Migrated from T4424 (view on Phabricator)

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information