Rename triggersRerun to cascade, and add new documentation

[aomarks]

First it was soft, then it was triggersRerun, now it's cascade (note we haven't released yet, so none of these changes were breaking).

This name came to me last night, and I kind of like it. I think soft is too vague and non-technical, but triggersRerun is just a mouthful (I've been typing it out a bunch, and it's been getting on my nerves). cascade feels like it sort of gives an impression of what the thing does, and I think will be memorable and understandable once you've read the docs.

Speaking of, I also rewrote the docs in a way that I hope is more clear.

Also adds some missing docs about dependencies and service to the configuration reference table.

Addon to #237

[augustjk]

Also do we need to make sure the docs site is synced with the readme?

[aomarks]

Also do we need to make sure the docs site is synced with the readme?

Yeah I haven't been keeping it up to date. Never publicized it, was kinda a work in progress. I've taken it down for now.