[Sound-open-firmware] revised SOF ABI change process now in effect

[Kai Vehmanen]

Hi all,

we’ve been working on some improvements to the SOF ABI change process 
since April this year, to address some of the issues seen in pull-req 
reviews at start of this year. The problem statement and resulting 
discussing can be seen at:

https://github.com/orgs/thesofproject/teams/sof-developers/discussions/35
https://github.com/thesofproject/sof-docs/pull/244 

The new process is now in effect and documented at:
https://thesofproject.github.io/latest/contribute/process/abiprocess.html

The main changes:
 - the process is now documented in sof-docs with a diagram
 - a new RFC step to discuss the interface before implementation is done
 - driver PR is no longer mandatory to be done at same time (but depends on type of change)
 - when driver+FW changes are both needed, driver change must be merged first 

Br, Kai