Kill the SIL :)

[Omikhleia]

The resilient manual still has several files in SIL (typically, the class chapter)

It also mentions SIL a lot (e.g. in package descriptions).

For people who use Markdown or Djot, the usage is not always straightforward. I am sure we can do better.

EDIT: Ideally, the user guide is intended for people with no knowledge of SIL, and even no knowledge of SILE and TeX-like typesetters, but just a basic knowledge of Markdown, to be at ease.¹ So it's ok to give pointers to SIL commands, or SILE Lua internals, but the main text body should eventually clear without knowing these things.

Footnotes

1. Even in-depth knowledge of YAML shouldn't be assumed, i.e. examples have to be clear enough so that users can start tinkering, and learn on the way. ↩

[Omikhleia]

Not going to do this for milestone 2.2.1 - Running late on everything.