Policy updates

[Ben Cotton]

As we've discussed, I've drafted two policy updates. This is your last
chance to provide feedback before I share them more widely

Policy change policy:
https://pagure.io/Fedora-Council/council-docs/c/6ecf22f6f15a0bff1854b16439ab...

Channel-specific ban policy:
https://pagure.io/Fedora-Council/council-docs/c/dfc10915306b2d9397dfcd2ed6fb...

I'll submit them as PRs and announce them (according to the terms of
the proposed policy change policy) tomorrow