- Indicate where xtask looks for wasi-sdk
- Indicate where `build --wasm` looks for and downloads wasi-sdk binary
to
- Mark native runtime as experimental, describe limitations
- Note ABI 13 support limitations
- Mention that `test --wasm` and `parse --wasm` require
`--features=wasm` build
Closes#374.
The statement about the intended backwards compatibility is purely
speculative and provided as a "straw man" to help reviewers come up with
a better description of the intended backwards compatibility.
