[11.6] Add parameters to `addVariable` on group level (#676)
[11.6] Add parameters to `addVariable` on group level (#676)

* Add parameters to addVariable on group level

Like masked

* Explicitly only allow the supported parameters, fixed typo, fixed phpdoc notation

* Update Groups.php

Co-authored-by: Graham Campbell <12930cf64b71914db9e5a6349ef004a734663c17@users.noreply.github.com>
m4tthumphrey/php-gitlab-api