Runlog: GitHub sync description request
Runlog: GitHub sync description request

`payu ghsetup` now prompts the user for an experiment description to be
used in the GitHub project.

Currently we don't append this to config.yaml but could do so in the
future.

marshallward/payu,aidanheerdegen/payu,nicjhan/payu,marshallward/payu,aidanheerdegen/payu