docs: update multi-agent tutorials to use Command

[vbarda]

No description provided.

[mathislindner]

Not sure if this is all intended, but I would like to add a comment to make sure this was not a mistake:
There are only conditional edges now (the old mermaid graph used to have uninterrupted edges)

should be:

This is the descriptive representation from the tutorial (where the agent ALWAYS reports back):

mermaid graph has changed to:

and here is the new mermaid graph that contradicts the intended behavior: it used to have uninterrupted arrows, but now it only has dotted arrows ( but the agent should always report back to the supervisor , no!?):