docs: fix broken managed databases link in migration guide (#4540)

Author: latent-9

docs/guides/migrating-off-hosted-managed-databases.md

@@ -1,6 +1,6 @@
 # Migrating off hosted managed databases
 
-Starting in sqlc 1.27.0, [managed databases](../docs/managed-databases.md) will require a database server URI in the configuration file.
+Starting in sqlc 1.27.0, [managed databases](../howto/managed-databases.md) will require a database server URI in the configuration file.
 
 This guide walks you through migrating to a locally running database server.