[DOCS] The document for SPIFFE no longer exists

[VariableDeclared]

Hi

The document linked at https://istio.io/latest/docs/ops/deployment/deployment-models/#trust-between-meshes not longer exists,

Cheers

Peter

[ericvn]

I can't move this to the istio.io repo and assign the the environments workgroup. I suspect the link changed with the recent Google Docs changes. @istio/wg-environments-maintainers

[craigbox]

This is an old doc from a VMware/Google collab in 2019. Can anyone recommend a better one?

[stevenctl]

cc @costinm, can you recommend a replacement resource?