main: rework usage

[leongross]

Remove unused switch case and improve/add command-specific usage from website.

[leongross]

From a cluttering perspective, I am unsure if we want to keep all the static usage messages in the middle of the code or refactor it somewhere else, something like const.go holding all that static data?

[dkegel-fastly]

The message is significantly longer now.... I wonder if we want the old version as the default, and the new one as "more help" somehow?

[leongross]

The old version is still there. I aligned the usage behavior to big go.
tinygo help displays the old message.tinygo help <subcommand> shows the additive help if there is any.

[leongross]

So with that in mind, what do you think? @dankegel @dkegel-fastly @deadprogram

[leongross]

@deadprogram what do you think of this?

[leongross]

If there are no change requests, can we merge this? @dankegel @archie2x @dkegel-fastly @dgryski

[dgryski]

LGTM

[archie2x]

I have have nits about the wording of things but more accessible documentation is great.

[dgryski]

Just noticed in my editor (not visible on github diff view) that there are a few lines with trailing space that should probably be cleaned up.

[aykevl]

I think this is an excellent idea! So if nobody objects, I'd like to see this merged :)
The only thing I'm worried about is keeping it in sync with the documentation at tinygo.org. I'm afraid we're going to forget updating the documentation in the code when we update the website.

[deadprogram]

@dgryski I think your change request was already made, no?

[leongross]

@aykevl keeping it in sync is also a problem I see. First, I think adding this for now is a big improvement to the current state. In the long run it mayb be a good idea to automatically pull this from the website source on a regular basis. I thought how to do this but since the webiste uses html amd css styling this is not trivial to convert.

[dgryski]

LGTM

[deadprogram]

Thank you very much for working on this @leongross and to @dgryski @aykevl @archie2x @dkegel-fastly for reviews. Now squash/merging.