Cut 0.8.0 release

This should have been cut after !17 (merged) was done since the current homebrew build is bugged for new users.

Steps:

1. Create and push the 0.8.0 tag off a known, working commit (or MR).
2. Monitor pipelines and observe binaries are built
3. Regenerate homebrew formula with brewer, commit and merge that
4. Update the IB image with the correct URL: (can steal this MR dsop/big-bang/bbctl!34 (merged))
5. Update docs / templates with new image (guided tour, docs, chart repo)