docs: v4 policyId param change

[avarobinson]

Is this a request for new documentation or updates to existing documentation
New Documentation / Existing Documentation
missing policy id change in v4 migration guide

If existing documentation, a clear summary of what needs to be changed
A clear and concise description of what documentation should be changed, and a link to the resource that needs the update.

If new documentation, a clear summary of what needs to be added
A clear and concise description of what documentation should be added.

Additional context
Add any other context or screenshots about the feature request here.