Release procedure

1. Generate clean go.mod: make generate_gomod
2. Push to master
3. Update missing documentation
4. Check snippets in documentation (sometimes first_line_contains or last_line_contains can change position and load too much)
5. Add breaking changes to UPGRADE-[new-version].md
6. Push to master
7. Add release in GitHub
8. Update Pub/Subs versions
9. Update and validate examples: make validate_examples