Link the changelog entry to its pull request

The entry names #9190, so the changelog points at this PR.

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

Author: JonoPrest

changes/type-path-memo.polish.md

@@ -1 +1 @@
-- Build: remember type path lookups within a compilation, which avoids looking up the same types such as `option` and `string` hundreds of thousands of times per build.
+- Build: remember type path lookups within a compilation, which avoids looking up the same types such as `option` and `string` hundreds of thousands of times per build. https://github.com/rescript-lang/rescript/pull/9190