Link the changelog entry to its pull request

The entry names #9192 and is filed under polish like the other build
speedups.

Signed-off-by: Jono Prest <jjprest@gmail.com>

Author: JonoPrest

changes/defer-dependency-signature-copy.internal.md

@@ -0,0 +1 @@
+- Build: copy a dependency's interface only when it is read, after the first copy of the same interface in a build, instead of every time a module checks whether the dependency is an alias. https://github.com/rescript-lang/rescript/pull/9192