how to extend Open Agentic with custom tools/plugins

[PAXECT-Interface]

Summary

Add a short documentation section that explains how to extend Open Agentic 2.0
with custom tools/plugins.

What to add

• A small new subsection in the README (or in a separate doc linked from the README)
  called something like "Extending with custom tools and plugins".

In that section, briefly show:

• how a simple tool is registered in agentic2_micro_plugin.py using the @tool decorator
  (for example, similar to the existing echo or summarize tools),
• and how a plugin from plugins.yaml (like legacy or meta) is exposed as a tool
  that can be used in the plan.

When this is done

• The README (or a linked doc) has a clear section that explains:
  • how to add a new @tool-based function,
  • how plugins from plugins.yaml (like legacy / meta) become usable tasks in a plan.
• New users can follow that section to create their own custom tool or plugin integration.