Fix documentation update during the release process

[cescoffier]

At the moment it fails with:

2019-12-19T15:11:07.9347234Z Cloning repo
2019-12-19T15:11:07.9364989Z Cloning into 'site'...
2019-12-19T15:11:15.6335143Z Warning: Permanently added the RSA host key for IP address '192.30.253.112' to the list of known hosts.
2019-12-19T15:11:15.6939235Z git@github.com: Permission denied (publickey).
2019-12-19T15:11:15.6957046Z fatal: Could not read from remote repository.
2019-12-19T15:11:15.6958973Z Copy content
2019-12-19T15:11:15.6960007Z 
2019-12-19T15:11:15.6962044Z Please make sure you have the correct access rights
2019-12-19T15:11:15.6964436Z and the repository exists.
2019-12-19T15:11:15.6982052Z cp: target 'site' is not a directory
2019-12-19T15:11:15.6984101Z yes: standard output: Broken pipe
2019-12-19T15:11:15.6985964Z Pushing
2019-12-19T15:11:15.6987855Z .build/doc.sh: line 14: cd: site: No such file or directory
2019-12-19T15:11:15.7140754Z HEAD detached at 0.1.2
2019-12-19T15:11:15.7142481Z nothing to commit, working tree clean
2019-12-19T15:11:15.7223939Z error: src refspec gh-pages does not match any
2019-12-19T15:11:15.7226207Z error: failed to push some refs to 'https://github.com/***/***-mutiny'

because it does not use the correct git url (it should use the https with token)