Reupload changelogs / readmes from Hackage

In https://github.com/haskell-compat/deriving-compat/issues/19, I encountered an issue that required retroactively changing the changelog for the package. I could upload a new minor release with this, but that seems like it's unnecessarily spamming Hackage. Similarly to how we can revise version bounds, could Hackage grant the ability to revise changelogs (or even readmes)?

Start by reading issue 19 and the existing mechanism for revising version bounds. Determine the policy and implementation scope for allowing changelog or README revisions without publishing a new package release; done means the supported behavior, authorization rules, and affected package metadata are defined and tested.

Written by the indexing model from the issue text.