Link to supply-chain details rather than including inline. (#6200)

Co-authored-by: Evan Anderson <[email protected]>

Author: knative-prow-robot

docs/reference/security/verifying-images.md

@@ -25,7 +25,12 @@ cosign verify-attestation \
   $IMAGE
 ```
 
-Note that the in-toto document is base64 encoded in the `.payload` attribute
+!!! note
+    Knative images are signed in `KEYLESS` mode. To learn more about keyless signing, please refer to
+    [Keyless Signatures](https://github.com/sigstore/cosign/blob/main/KEYLESS.md#keyless-signatures)
+    Our signing identity(Subject) for our releases is `[email protected]` and the Issuer is `https://accounts.google.com`
+
+The in-toto document is base64 encoded in the `.payload` attribute
 of the attestation; you can use `jq` to extract this with the following
 invocation:
 

docs/snippets/security-prereqs-images.md

@@ -1,21 +1,2 @@
-## Verifying image signatures
-
-Knative releases from 1.9 onwards are signed with [cosign](https://docs.sigstore.dev/quickstart/quickstart-cosign/).
-
-1. Install [cosign](https://docs.sigstore.dev/cosign/system_config/installation/) and [jq](https://stedolan.github.io/jq/).
-
-1. Extract the images from a manifeset and verify the signatures.
-
-```bash
-curl -sSL {{ artifact(repo="serving",file="serving-core.yaml") }} \
-  | grep 'gcr.io/' | awk '{print $2}' | sort | uniq \
-  | xargs -n 1 \
-    cosign verify -o text \
-      --certificate-identity=signer@knative-releases.iam.gserviceaccount.com \
-      --certificate-oidc-issuer=https://accounts.google.com
-```
-
-!!! note
-    Knative images are signed in `KEYLESS` mode. To learn more about keyless signing, please refer to
-    [Keyless Signatures](https://github.com/sigstore/cosign/blob/main/KEYLESS.md#keyless-signatures)
-    Our signing identity(Subject) for our releases is `[email protected]` and the Issuer is `https://accounts.google.com`
+Optionally, you may choose to [verify the images before installing](/docs/reference/security/verifying-images.md).
+You may also need the image verification information if your cluster is configured to verify image signatures during pod execution.