Update "Terraform Core Architecture Summary" doc (#27897)
Update "Terraform Core Architecture Summary" doc (#27897)

* Update Godoc links from godoc.org to pkg.go.dev

* Update reference to renamed GraphNodeResource interface

Ref hashicorp/terraform#24389

* Update dead links; minor formatting adjustments

* Add FIXME item following deprecation of EvalNode
hashicorp/terraform,rnaveiras/terraform,rnaveiras/terraform,hashicorp/terraform,apparentlymart/terraform,apparentlymart/terraform,tommynsong/terraform,ewbankkit/terraform,apparentlymart/terraform,ewbankkit/terraform,tommynsong/terraform,tommynsong/terraform,apparentlymart/terraform,rnaveiras/terraform,ewbankkit/terraform,hashicorp/terraform,apparentlymart/terraform,ewbankkit/terraform