Document how to update the CUE schemas

Signed-off-by: Stefan Prodan <[email protected]>

schemas/README.md

@@ -0,0 +1,23 @@
+# Timoni CUE Schemas
+
+The Timoni's CUE schemas are included in the modules generated with `timoni mod init`.
+
+## Vendoring
+
+To update a module's schemas to the latest version,
+run the following command from within the module root:
+
+```shell
+timoni artifact pull oci://ghcr.io/stefanprodan/timoni/schemas:latest \
+  --output cue.mod/pkg
+```
+
+To update the schemas and verify the signature with Cosign v2:
+
+```shell
+timoni artifact pull oci://ghcr.io/stefanprodan/timoni/schemas:latest \
+  --verify=cosign \
+  --certificate-identity-regexp="^https://github.com/stefanprodan/timoni.*$" \
+  --certificate-oidc-issuer=https://token.actions.githubusercontent.com \
+  --output cue.mod/pkg
+```