How to upload haddocks to Hackage?

This doesn't seem to be documented anywhere, but implicit in the help messages for upload. WHere do i look to find this information?

**UPD (2025):**

This is currently documented at the bottom of https://hackage.haskell.org/upload, and, in its simplified form, looks as follows:

```
$ cabal haddock --enable-doc --haddock-for-hackage
$ cabal upload --documentation ./dist-newstyle/*-docs.tar.gz
```

Start with the upload help messages referenced in the issue and compare them with the documentation currently shown at https://hackage.haskell.org/upload. Confirm the documented cabal haddock and cabal upload workflow, then identify the appropriate Cabal documentation location; done means a newcomer can find and follow the complete process.

Written by the indexing model from the issue text.