doc: licence information

Improve GPLv3 licence information like here https://lab.frogg.it/lydra/yunohost/ansible-yunohost/-/tree/main#license You can see an exemple here

• add icon/logo and little texte in readme

• add licence file

• add Lydra Copyright https://gitlab.com/lydra/gitlab-ci-templates/-/blob/master/LICENSE#L634

• https://choosealicense.com/licenses/gpl-3.0/

• https://www.gnu.org/licenses/quick-guide-gplv3.html