doc: repl: add defineComand and displayPrompt

[bengl]

Also some minor edits so the additions make sense.

I've used defineCommand several times now, figuring out how to use it by viewing the source. I figured it probably should be documented.

[Trott]

Nit: const instead of var?

[bengl]

Other pre-existing examples in the doc use var for such things, so I thought it was best to keep with the style already in this doc. Perhaps instead a future PR can convert them all in one fell swoop?

[Trott]

Sure. It's a nit. Ignore it.

[bengl]

Cool beans.

[Trott]

LGTM with one typo correction that should happen and a bunch of nits that can be ignored if you wish because they are, you know, just nits.

[bengl]

Cool, yeah, I think the vars should stay for consistency until a full overhaul is done. Other than that, those nits are addressed now I think.

[jasnell]

LGTM

[bengl]

OK, @Trott helpfully pointed out a conflict with master and it seems due to 8a245ea, but that was easy to resolve, so here's a rebased version. I also restored the link URLs to the bottom of the file.

[Trott]

LGTM

[Trott]

Landed in 061b2c8

[tflanagan]

Not to be a doc-nazi, but could we put the class definition first, and then resort alpha?

[Trott]

@tflanagan Whoops! Did we just mess up a bit of the alphabetizing work that you and jasnell did? Sorry about that. Since this is now merged with master, we'll want a separate PR to re-alphabetize. Do you want to put together a PR on this file for it? I'm happy to do if you'd rather not.

[tflanagan]

@Trott no worries! I figured this would happen once or twice :) I'll take care of it on Monday

[MylesBorins]

landed in v4.x-staging in 5254fda