Incorrect info on closures capturing individual struct fields

[theemathas]

The reference page on closure types states the following:

Composite types such as structs, tuples, and enums are always captured entirely, not by individual fields. It may be necessary to borrow into a local variable in order to capture a single field

As of edition 2021, this is not true. See the edition guide.

[ehuss]

Thanks for the report! I believe this is a duplicate of #1066, so closing in favor of that. Coincidentally, I was looking at getting it updated again, so hopefully we'll get some movement.