Refine and expand repository level documentation

[cdcabrera]

Description

With the addition of the http transport work #23 and in progress tool plugin work #22 our single file documentation is quite the scroll. Breakout docs out into component parts targeted at audiences, ie. consumer, contributor, and agent.

Acceptance criteria

• Repo documentation is broken down into audience targets
  • PR template - links to contributor docs
  • README - quick implementation and directions to sub docs
  • CONTRIBUTING - contributor and tooling guidelines, requirements
  • DOCS - consumer "how to user"
  • guidelines/* - agent targeted documentation complementing user docs
• Documentation base is already setup under existing work started with MCP tools should be expandable via tool-plugins #22