update the readme (stale function refs, etc)

[pq]

https://github.com/monome/norns/blob/master/readme-script.md

contains a bunch of stale references that are confusing folks.

see for example:

https://llllllll.co/t/norns-scripting/14120/76

[okyeron]

Would it be reasonable to take these Readme items and add them to the wiki section?

I would volunteer to do so if needed.

[simonvanderveldt]

@pq wouldn't it make sense to generate these docs as well? Similar to the issue created for dust

[pq]

@simonvanderveldt: maybe! are you thinking the docs could be embedded in source somehow? curious what you're thinking...