[RFC-0003] OCI select layer by media type

Signed-off-by: Stefan Prodan <stefan.prodan@gmail.com>

rfcs/0003-kubernetes-oci/README.md

@@ -4,7 +4,7 @@
 
 **Creation date:** 2022-03-31
 
-**Last update:** 2022-08-11
+**Last update:** 2022-08-22
 
 ## Summary
 
@@ -134,6 +134,18 @@ spec:
       name: cosign-key
 ```
 
+### Layer selection
+
+By default, Flux assumes that the first layer of the OCI artifact contains the Kubernetes configuration.
+For multi-layer artifacts created by other tools than Flux CLI, users can specify the media type of the layer
+which contains the tarball with Kubernetes manifests.
+
+```yaml
+spec:
+  layerSelector:
+    mediaType: "application/vnd.cncf.flux.content.v1.tar+gzip"
+```
+
 ### Pull artifacts from private repositories
 
 For authentication purposes, Flux users can choose between supplying static credentials with Kubernetes secrets