Update build apps overview with Gaia link

Co-authored-by: Thomas Osmonson <aulneau@users.noreply.github.com>

src/pages/build-apps/overview.md

@@ -18,7 +18,7 @@ Three main integrations are available:
 
 - **Authentication**: Register and sign in users with identities with the Stacks blockchain
 - **Transaction signing**: Prompt users to sign and broadcast transactions to the Stacks blockchain
-- **Data storage**: Save and retrieve data for users with Gaia
+- **Data storage**: Save and retrieve data for users with [Gaia](/build-apps/references/gaia)
 
 All three of these integrations can be used together to create powerful new user experiences that rival or exceed those of traditional apps – all while protecting your users' digital rights.