Update External-Commands docs for new command abstraction

[dduugg]

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[apainintheneck]

Do we need to communicate that the old way of defining a command is valid for now?

[MikeMcQuaid]

Do we need to communicate that the old way of defining a command is valid for now?

I don't think so. We don't really want new commands created that way.

[MikeMcQuaid]

It might make sense to mention that args is available in all instance methods too.

Doing this in a follow-up PR would be nice 👍🏻

[MikeMcQuaid]

Thanks again @dduugg!

[dduugg]

Do we need to communicate that the old way of defining a command is valid for now?

I don't think so. We don't really want new commands created that way.

That's my thinking. I intend to add deprecation warnings once i've updated commands in various taps.