Add diagrams for rpc routing and acl entity relationship
contributing: create directory structure for new docs
WIP diagram for catalog entities
Add overview diagram
Co-Authored-By: Kelly Devlin <kdevlin@hashicorp.com>
The main branch is being renamed from master->main. This commit should
update all references to the main branch to the new name.
Co-Authored-By: Mike Morris <mikemorris@users.noreply.github.com>