Github issues now supported by the failure exporter

[weshayutin]

Check out the Github Issues failure exporter and please provide your feedback!
https://github.com/konveyor/pelorus/blob/master/docs/Configuration.md#instance-config-github

[mateusoliveira43]

Closing as we have this documented in the read the docs website

• https://pelorus.readthedocs.io/en/latest/GettingStarted/Overview/#supported-providers
• https://pelorus.readthedocs.io/en/latest/UpstreamSupport/#failure-exporter