doc: fix link to postgres.md and database.md

Change-Id: I37237bb48a5eaa4b9517850b7414f10363a9934e
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/237939
Reviewed-by: Jamal Carvalho <jamalcarvalho@google.com>
Reviewed-by: Andrew Bonventre <andybons@golang.org>
diff --git a/doc/frontend.md b/doc/frontend.md
index 067c154..de86796 100644
--- a/doc/frontend.md
+++ b/doc/frontend.md
@@ -30,8 +30,8 @@
 postgres database.
 
 Alternatively, you can run pkg.go.dev with a local database. See instructions
-on how to [set up](doc/postgres.md) and
-[populate](doc/worker.md#populating-data-locally-using-the-worker)
+on how to [set up](postgres.md) and
+[populate](worker.md#populating-data-locally-using-the-worker)
 your local database with packages of your choice.
 
 You can then run the frontend with: `go run cmd/frontend/main.go`