Specify the HTTPS URL of the GitHub Organization / User Account and repository.
GitHub examples:
- https://github.com/jenkinsci/github-branch-source-plugin
- https://github.com/jenkinsci/github-branch-source-plugin.git
GitHub Enterprise examples:
- https://myccompany.github.com/jenkinsci/github-branch-source-plugin
- https://myccompany.github.com/jenkinsci/github-branch-source-plugin.git