* Add some notes, remove open issue, fix mistakes & formatting
- Remove Open Issue “How far should this be backported?”.
That'll be up to release managers, no need to put it in the PEP.
- Add a section on adding filters to zipfile. Not *quite* a
“rejected idea”, but IMO the PEP is good enough without it.
- Add a note on a registration mechanism
- Fix a few obvious mistakes, typos, formatting
Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>