Add documentation on getting an account on TGCC

[lucas-ige]

The title says it all :)

[charlesamory]

to add :

• downlad the form from the DARI website. Any new account request requires that your collaborators first submit a request to be affiliated with your project. To assist you with this new process, documentation is available on the DARI website: https://www.edari.fr/documentation/index.php/Documentation_compl%C3%A8te#ModalitesAccesCalculateurs
• provide an ip adress and setup a tunnel ssh though ssh.ige
• reach out to the IT department to fill and sign the form
• take a look at the TGCC documentation