Update getting_started.md

[b-k-schneider]

HI, just trying out things from the documentation, and it seems that TARGET_DUTY, TARGET_FILTER_FREQ (and maybe others) are not working giving the error message (for example):
Traceback (most recent call last):
File "", line 1, in
AttributeError: module 'alles' has no attribute 'TARGET_DUTY'

Is this something to update in the documentation?
Commands found in: https://github.com/shorepine/alles/blob/main/getting-started.md

[bwhitman]

You're right -- we have not updated the getting started page. I know it's a bit messy, but please use the AMY README for more up to date documentation on the synth in Alles. https://github.com/shorepine/amy

I will keep this open as a task to update this getting started page, thanks