Seems reasonable (though personally I'd like to see user-facing docs moving out of the main repo). The most difficult part about standardizing conventions is the politics though.
It's conceptually a precursor. At the moment it can't be used as an extended standard library because suitable technology doesn't exist in the stack. Needs cargo metapackages. But it or something like it could fill the same role as the proposed platform metapackage, unofficially.
There's a promising, completely automatic solution for this in the wings by the author of crates.fyi. Not sure if it's been announced publicly yet, but it's going to be pretty nice.