Adds the ability to use name_first_letter in site setting external system avatars url.
The default value for external system avatars url is
/letter_avatar_proxy/v2/letter/{first_letter}/{color}/{size}.png
This plugin allows you to use
/letter_avatar_proxy/v2/letter/{name_first_letter}/{color}/{size}.png
to have the avatar letter be the first letter or number in the user's name. If there is no name or it contains no letters or number, the first letter of the username is used. This affects all users who do not have a custom avatar. If the user changes their name, the avatar letter will change accordingly.
To install, follow the Install a Plugin howto.