doc: correct the method registerNamshiProvider PHPdoc description

[t49tran]

Thanks for putting this useful Library together.

This PR is to correct the PHPDoc description for the AbstractServiceProvider::registerNamshiProvider method.

[eschricker]

Hi @t49tran,
due to the inactivity of the project, we have forked the repository (https://github.com/PHP-Open-Source-Saver/jwt-auth). Currently we are going through the PR and identify which are relevant for us. It would be great if you would recreate your PR in our repository.

[t49tran]

Hi @t49tran, due to the inactivity of the project, we have forked the repository (https://github.com/PHP-Open-Source-Saver/jwt-auth). Currently we are going through the PR and identify which are relevant for us. It would be great if you would recreate your PR in our repository.

Sounds good to me @eschricker