Mail content should be more explicit

content of the email sent for an invitation should be changed by:

"Hello ,

You have been granted permissions to access

{document_name}

.

Username and password are required for connection:

• username already defined is {email}
• password: you have to define it by validating your invitation through this {link_to_login_registration}

Once password created, you'll be able to log in to the application and access

{document_name_link}

.

The Nuxeo Platform Administrators team."