Mention 5036fd9c6e9b89809f93a6ffa17ac6663652baed in release notes for 2.0.9

[asomers]

Could you please update the release notes to describe change 5036fd9 ? It caused mockall to fail in some cases, and I was surprised to see a breaking change missing from the release notes.

The offending syntax is

/// method doc comment
fn boo(&self);

when parsing this as an ImplItem, syn 2.0.8 would parse it as an ImplItem::Fn, but syn 2.0.9 parses it as ImplItem::Verbatim.

[dtolnay]

Done — sorry about the breakage.