* Build docs with the nightly toolchain so [foo::bar] links work by
default. This is a relatively new feature of rustdoc and I thought it
was stabilized at this point but apparently it's not!
* Tweak some API docs on `wasmtime::Strategy`
* Use `--all` to build all local crate documentation instead of trying
to list the number of local crates
* Tweak some documentation configuration to avoid warnings generated by
Cargo.
d142a39113