Documenting the fact that the sync module is runtime agnostic

[jofas]

In this URLO topic, OP is looking for a runtime agnostic channel implementation supporting both sync and async operations. I remembered reading somewhere that everything in the sync module is runtime agnostic.¹ I expected this to be stated in the documentation of the sync module, but alas, only in the sync::mpsc module the docs mention that the channel is runtime agnostic.

In response to the above-mentioned URLO topic and #4232, I was wondering if the docs could be improved to make it clearer that everything in sync is runtime agnostic, not just the mpsc channel. For me a small section in the docs of the sync module would've been sufficient, but of course, this is just a suggestion and there might be better ways to document what parts of Tokio are runtime agnostic and what parts aren't.

FYI I'd be interested in whipping up a PR if this is a desired fix and there is consensus on what should be documented and where to put it.

Footnotes

1. Barring one exception. ↩

[Darksonn]

I think it would be great to have a section in the sync module docs about runtime compatibility.