867317835d
Improve documentation for file locking Add notes to each method stating that locks get dropped on close. Clarify the return values of the try methods: they're only defined if the lock is held via a *different* file handle/descriptor. That goes along with the documentation that calling them while holding a lock via the *same* file handle/descriptor may deadlock. Document the behavior of unlock if no lock is held. r? `@m-ou-se` (Documentation changes requested in https://github.com/rust-lang/rust/issues/130994 .)