[DOCS] Hooks Basic usage should include bare minimum example of usage for Registering Individual Hook Callbacks

[pragmaticivan]

Documentation Section

docs/user-guide/concepts/agents/hooks.md

Under (Registering Individual Hook Callbacks)

Current State

Currently, the variable hook in the example is not defined anywhere.

Suggested Improvement

Add example with imports and bare minimum code to get this working with an agent

Rationale

Honestly, learning the project from scratch by reading the docs first, and can't tell you where the hooks variable is coming from.

Additional Context

No response

[dbschmigelski]

Hi, will update, thanks for calling this out.

For context, the hooks object comes from the agent. It should be agent.hooks.add_callback

[pragmaticivan]

Done with https://github.com/strands-agents/docs/pull/203/files