Leveling Up - Uploading a package to hackage

file to edit: https://github.com/haskell/cabal-userguide/blob/main/src/leveling_up/06_uploading_package_to_hackage.md

## Brief Summary

This (like haddocks #22) is another poorly documented area. This section should cover common considerations (versioning, globally unique names), the relevant metadata in the `.cabal` file that will make it on to hackage, and the process of uploading a library to hackage.

Edit src/leveling_up/06_uploading_package_to_hackage.md. Start by reading the existing section, then organize guidance around versioning, globally unique package names, .cabal metadata published to Hackage, and the library upload process. Done means the section clearly covers these common considerations and steps.

Written by the indexing model from the issue text.