DOC: Make UP006 easier to find

[MartinThoma]

This change makes it easier to understand what UP006 is about. It also makes it easier to find the rule when you only know the effect, but not the PEP.

[not-my-profile]

These Markdown tables in the README are autogenerated from our format strings in the Rust code and we don't want to change that format string to Use `dict` / `list` instead of `typing.Dict / typing.List` for type annotations since it would make the actual error messages less descriptive.

You are correct to note that the error format strings often aren't easy to understand. However we want to address this by introducing more thorough documentation #1467, rather than hardcoding specific values in our format strings.

[MartinThoma]

Makes sense to me :-) I'm closing this as it's included in #1467. However, #1467 is pretty general. It would be nice to doc a single example rule well and then let the community help with following that example

[not-my-profile]

Yes I agree :) However we firstly have to set up the documentation system ... we haven't done so yet since we're currently focusing on other issues but it's very much on our minds and the roadmap.

[charliermarsh]

Want this to get much better!