vignette about scmake vs remake::make

Should answer questions including:
* What does scmake do that is different from remake::make? Does the make version of this function do unnecessary things? Does it fail to recognize changes to cached things?
* Could you use remake::make alongside some scipiper functions, e.g., create_task_makefile and loop_tasks, and when might that be beneficial?
* What's a shared cache?
* If a project, or perhaps even a target within a project, doesn't have an .ind file, is it equally safe to run `scipiper::scdel` or `remake::delete`, or does `scdel` do something else too?