bug: "agent agentic-workflows update" and "agent agentic-workflows upgrade": please update docs

[bmerkle]

@Copilot please update the documentation page https://githubnext.github.io/gh-aw/setup/agentic-authoring/

There are two places (see anchors below) where commands for "update" and "upgrade" are decribed.
I am not 100% sure, but i think the page is out of date and should be updated.

In copilot cli (version 0.0.389) we only have the option upgrade. (see option 4)
❯ 1. Default (current)
2. create-agentic-workflow
3. debug-agentic-workflow
4. upgrade-agentic-workflows
5. Cancel (Esc)

update is NOT available as separate command.

https://githubnext.github.io/gh-aw/setup/agentic-authoring/#how-to-use-the-agentic-workflows-agent

Update an existing workflow to add features or modify behavior
Upgrade workflows to new gh-aw versions or fix deprecations

https://githubnext.github.io/gh-aw/setup/agentic-authoring/#how-to-use-the-agentic-workflows-agent

Update a workflow

/agent agentic-workflows update add web-fetch tool to issue-classifier

Upgrade workflows

/agent agentic-workflows upgrade all workflows to latest version

[pelikhan]

All the custom agents have been merged into one. If you run "upgrade" with the latest release, it should clean up you repo.

[pelikhan]

Try

gh aw upgrade