Link callback formatting changelog entry to PR

Signed-off-by: Christoph Knittel <ck@cca.io>

Author: cknitt

CHANGELOG.md

@@ -35,7 +35,7 @@
 
 #### :bug: Bug fix
 
-- Fix unstable formatting of trailing comments in nested callbacks. https://github.com/rescript-lang/rescript/issues/6976
+- Fix unstable formatting of trailing comments in nested callbacks. https://github.com/rescript-lang/rescript/pull/8627
 
 - Fix excessive parentheses and indentation in function assignments to refs, align record and array assignment formatting across refs and fields, and preserve function return-type parentheses and consistent JSX fragment layout in callbacks. https://github.com/rescript-lang/rescript/pull/8611
 - Fix a recursive module with an empty signature discarding its right-hand side. Lambda-to-Lam conversion rewrote `Pupdate_mod` to unit when the module's shape had no fields, dropping the primitive's arguments - one of which is the right-hand side - so `module rec M: {} = { let () = Console.log("effect") }` emitted nothing for `M`. The elision now happens where the bindings are produced, with the right-hand side still in hand. https://github.com/rescript-lang/rescript/pull/8608