Docs for deprecated RPC interface to agents is confusing

[mkeeler]

Overview of the Issue

We have this docs page to cover the ancient RPC interface to Consul agents that came before the agent's supported an HTTP API.

https://www.consul.io/docs/agent/rpc

There have been reports of some confusion about Consul still performing RPC traffic even though this page says its deprecated. As its a source of confusion we should probably change things

Proposed Solution

• We should remove the page all together now that we have versioned docs and the feature has been gone for 14 major releases.