Document `exports` in package.json's (for the regular use and for within `publishConfig`)

[Ayc0]

• I'd be willing to implement this feature (contributing guide)
• This feature is important to have in this repository; a contrib plugin wouldn't do

Describe the user story

publishConfig can be used to override some top level fields on publish.
According to https://yarnpkg.com/configuration/manifest#publishConfig, you can only set in it:

• access
• bin
• browser
• executableFiles
• main
• module
• registry
• type

But not exports. To note: exports field replaces main, module, and type so it'd make sense to support it

According to #5874, exports does work in here, but I haven't tested it myself.

Describe the solution you'd like

Support exports in publishConfig

And if it's already supported, document it

Describe the drawbacks of your solution

None

Describe alternatives you've considered

None

[merceyz]

And if it's already supported, document it

Support was added in #2431 so this is indeed a documentation issue.

[Ayc0]

Support was added in #2431 so this is indeed a documentation issue.

Amazing! I can draft a PR if you want

[Ayc0]

Actually, even exports isn't documented in the top level package.json. So it's not related to just publishConfig