allowed-unused-imports has incorrect documentation

[tylerlaprade]

• In the docs, it's part of the lint section rather than lint.pyflakes
• In those same docs, "thought" is used in place of "though"
• The TOML schema doesn't recognize the setting at any of the three possible levels.

[zanieb]

We should allow defining this either at lint or lint.pyflakes from my read of the code.
I presume the schema store has just not been updated since the last release.

Typo fix at #13669

[zanieb]

SchemaStore/schemastore#4131

[tylerlaprade]

Thanks! Is there precedent for allowing other settings at two different levels? It seems a bit confusing.

[zanieb]

I'm not sure honestly. It does seem confusing if it's not necessary for some reason. cc @charliermarsh who reviewed that contribution.

[charliermarsh]

It should only be under lint.pyflakes.