We've backported it from 0.25 into 0.24 (aka 1.18). We should probably add a note to document it.

Upstream docs are here https://knative.dev/docs/admin/serving/feature-flags/#emptydir. We probably want to just add a note to our docs, saying that we support this and how to enable it for users.

To enable it in Openshift Serverless, the following has to be adjusted in the KnativeServing object

spec:
  config:
    features:
      "kubernetes.podspec-volumes-emptydir": enabled