docs: update image signature context

Signed-off-by: Jordi Teterissa <[email protected]>

Author: jordi-t

README.md

@@ -122,7 +122,7 @@ software components and build dependencies.
 
 ## Image Signatures
 
-CloudNativePG container images are securely signed using
+The [`minimal`](#minimal-images) and [`standard`](#standard-images) CloudNativePG container images are securely signed using
 [cosign](https://github.com/sigstore/cosign), a tool within the
 [Sigstore](https://www.sigstore.dev/) ecosystem.
 This signing process is automated via GitHub Actions and leverages