Help docs

[NaitLee]

It’s always been “Coming soon.” I finally got a (hopefully) good way to do help docs (and more) with a little innovation.
(It’s not something “mature,” in contrast to XML or Markdown. I just hope it may help, in some aspects.)

It’s in this branch.
The (small) infrastructure is almost complete. We can start to write now.
They are here.

Let’s pay attention to “helps” that you want — spread problems you (have) met here.

[NaitLee]

This will be closed in place of #60