Document msrv toolchain per chip hal

[MabezDev]

[SergioGasquez]

LGTM! Was this + intended?

[jessebraham]

Few things:

1. There doesn't seem to be a version listed for the esp toolchain, are you proposing we only support the latest release?
2. The MSRV stated for RISC-V does not match what is in the CI workflow or in the MSRV section of the README
3. The MSRV section in the README probably can be removed; if we duplicate the info it's almost surely going to fall out of sync at some point

[bjoernQ]

I agree having a version on the toolchain also for Xtensa would make sense - then everything is in one place

Dropping the chapter on the MSRV is also probably good since it's almost duplicated then - we will just loose the hint on RUSTC_BOOTSTRAP=1 - not sure if we lose much

[bjoernQ]

LGTM!

[MabezDev]

I've made the documentation changes, however, I'm not sure what to do about the actual CI checks.

For reference, the reason I'm adding this info is that any esp-hal version <0.14 will stop working after nightly-2023-11-30 and/or 1.76 stable, but 0.14+ (and the main branch) will work on any compiler post nightly-2023-11-30. Therefore I don't think we actually need to change any CI checks, and when 1.76 rolls around we can go back to stable for our RISC-V targets.

[bjoernQ]

LGTM - we could mention the thing about versions < 14 and version 14+ and their requirements ... but on the other hand we probably should document the current requirement here

If it causes confusion we can still change it

[jessebraham]

For now I'll just merge this, and will do a full review of things again before releasing. If we decide to make any changes we can then, not the end of the world.

So, LGTM, thanks!