Mention that goto-def works with println, which is big!

Author: matklad

thisweek/_posts/2019-12-09-changelog-2.md

@@ -8,6 +8,7 @@ Commit: [`e3a9e80`](https://github.com/rust-analyzer/rust-analyzer/commit/e3a9e8
 
 ## New Features
 
+* [`#2500`](https://github.com/rust-analyzer/rust-analyzer/pull/2500) goto definition works inside `format!`-like macros.
 * [`#2477`](https://github.com/rust-analyzer/rust-analyzer/pull/2477) pass the right `--edition` to `rustfmt`
 * [`#2479`](https://github.com/rust-analyzer/rust-analyzer/pull/2479) support some build-in derives
 * [`#2492`](https://github.com/rust-analyzer/rust-analyzer/pull/)2492, [`#2494`](https://github.com/rust-analyzer/rust-analyzer/pull/2494) goto definition and syntax highlighting work properly for type parameters