Update communicate-with-javascript.md

[davesnx]

I managed to fix some of the feedback I found while revisiting the documentation with JS.

I tried to suggest stuff and annotate some of my feedback as comments.

We can discard as many as we want, no need to apply any of that, but would be nice to have some fixes

[jchavarri]

@davesnx thanks for the suggestions. I think I asked or addressed all of them. Once we go through them and get to an understanding / agreement, I can open a PR that just applies them (or just use this one).