Remove `resource` docs once entity registry is created

[jsuereth]

Area(s)

No response

What's missing?

We'd like to remove the resource docs folder in favor of fully auto-generated documentation in the entity registry.

Post #2278 We will need to do the following:

• Move /docs/resource/process.md#selecting-process-attributes into YAML
• Move /docs/resource/README.md content into new location (naming conventions, special attributes, etc).
• Move useful resources links from /docs/resource/k8s.md into YAML somewhere
• Move /docs/resource/cloudfoundry.md descriptive content into YAML somewhere
• Move /docs/resource/cicd.md descriptive content into description/brief for groups.
• Move /docs/resource/browser.md general note on the group into note on the group.
• Move /docs/resource/cloud-provider/gcp/apphub.md general note into a namespace note (may need weaver support)

Describe the solution you'd like

No response

[thompson-tomo]

The namespace note support has been implemented via: open-telemetry/weaver#849