message: clarify what goes into "*-sys" crates
diff: @@ -371,8 +371,8 @@ pieces of functionality:
  * The library crate should link to the native library `libfoo`. This will often
  probe the current system for `libfoo` before resorting to building from
  source.
  -* The library crate should provide **declarations** for functions in `libfoo`,
  - but **not** bindings or higher-level abstractions.
  +* The library crate should provide **declarations** for types and functions in
  + `libfoo`, but **not** higher-level abstractions.
  The set of `*-sys` packages provides a common set of dependencies for linking
  to native libraries. There are a number of benefits earned from having this
  