chore(ci): Generate cosign bundle for binaries (#1993)

Generate a cosign bundle file to help with verifying the binaries.

Signed-off-by: Charith Ellawala <charith@cerbos.dev>

.goreleaser.yml

@@ -95,7 +95,7 @@ signs:
       - --yes
       - --rekor-url
       - https://rekor.sigstore.dev/
-      - "--output-signature=${signature}"
+      - "--bundle=${artifact}.bundle"
       - "${artifact}"
     artifacts: all
 

docs/modules/ROOT/pages/installation/container.adoc

@@ -7,6 +7,18 @@ include::partial$attributes.adoc[]
 docker run --rm --name cerbos -p 3592:3592 {app-docker-img}
 ----
 
+[NOTE]
+====
+
+Cerbos images can be verified using link:https://www.sigstore.dev[sigstore] tools as follows:
+
+[source,sh,subs="attributes"]
+----
+cosign verify --certificate-oidc-issuer="https://token.actions.githubusercontent.com" --certificate-identity-regexp="github.com/cerbos/cerbos" {app-docker-img}
+----
+
+====
+
 By default, the container is configured to listen on ports 3592 (HTTP) and 3593 (gRPC) and watch for policy files on the volume mounted at `/policies`. You can override these by creating a new xref:configuration:index.adoc[configuration file].
 
 .Create a directory to hold the config file and policies.
@@ -37,3 +49,5 @@ docker run --rm --name cerbos -d -v $(pwd)/cerbos-quickstart:/quickstart -p 3592
 ----
 
 NOTE: Cerbos container images are mirrored to Docker Hub and the latest version is available at {app-alternative-docker-img} as well.
+
+