Incorrect Sample | Call out to an HTTP endpoint and cache the response.policy.xml

The policy https://github.com/Azure/api-management-policy-snippets/blob/master/examples/Call%20out%20to%20an%20HTTP%20endpoint%20and%20cache%20the%20response.policy.xml is referred to the APIM cache-response document: https://docs.microsoft.com/en-us/azure/api-management/policies/cache-response

When running the policy we can see the error while saving the policy. Please fix the policy so it is reflected correctly in the APIM document.

MicrosoftDocs/azure-docs#95685

Open the referenced examples/Call out to an HTTP endpoint and cache the response.policy.xml file and compare it with the linked APIM cache-response documentation. Reproduce the policy-save error if possible, then verify that the corrected sample matches the documented policy and can be saved successfully.

Written by the indexing model from the issue text.