Document support policies

[leofang]

• We support CUDA minor version compatibility
• For the current cuda-python packages (future cuda.bindings #75):
  • We cover bindings for the latest two CUDA major versions. The way we do this is to maintain 2 branches: main for the latest major cuda-N and the last major cuda-<N-1>, and we backport bug fixes that are merged into main to the last major branch as well.
  • For versioning, we follow the same CTK major.minor version, but use the patch version for Python only changes. Reasoning being that no API addition/removal is expected in CTK patch releases.
  • For a diagrammatic representation please see #105
• We follow CPython's EOL schedule (important: not SPEC 0 or NEP 29!)
• ... anything else?

[vzhurba01]

but use the patch version for Python only changes.

Cython changes as applicable are also allowed as long as we don't break ABI compatibility. Since the Runtime bindings currently uses a Cython reimplementation, any fixes going into that layers is OK since it's private.

[leofang]

@aterrel interested in work stealing? 😆