Auto merge of #13496 - rust-lang:lnicola-patch-1, r=jonas-schievink
Auto merge of #13496 - rust-lang:lnicola-patch-1, r=jonas-schievink

internal: Clarify feature policy

CC #13495

rust-analyzer/rust-analyzer,rust-analyzer/rust-analyzer,rust-analyzer/rust-analyzer,rust-analyzer/rust-analyzer,rust-analyzer/rust-analyzer