The links now redirected to docs.github.com. `common SSH problems` link
is misredirected to `Authenticating to GitHub` page, so it has been
corrected to the proper `troubleshooting SSH` page.
Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>