Customizing the '[BLOG NAME] Your username and password' mailing

I have a site that I am creating user to different roles (ie Contributor). If you select the option from within ‘Add New User’ page, it automatically sends the user an email with ONLY their User and Password. I want to add more content in this mailing (ie. Helpful tutorial Links, Support Emails, and Welcome message, etc.etc. etc). Here is a link to a sample of the screens and email that I am referencing: https://theblogsociety.com/images/CustomizedEmail.jpg

If anyone in WP Land can help I would be most appreciative. Even might give you some FREE Ad space on the site in which I am referencing! TY.

FYI: I am hosting on my own server