Add automation to production and staging deployments

[lparisc]

Automate the docsgen scripts further when deploying to production and staging

AC:

• Merge docsgen repo staging branch to main
• Add functionality to clone docsgen repo so that...
  • main branch is checked-out/pulled when deploying to production site
  • staging branch is checked-out/pulled when deploying to staging site
• Then invoke clean_rebuild.sh script as usual

[nsjames]

Docsgen was rewritten into https://github.com/eosnetworkfoundation/docs-ui

Since we never had a ticket for it, I'll just close this one as done instead of discarded.