message: Fix typo in README: async is a wrapper around sync
  The README claims that the sync interface is a thin wrapper around the async interface, but as far as I can tell the inverse is true.
diff: @@ -115,7 +115,7 @@ The minimum supported Rust version is 1.41.0.
  The Rust ecosystem has a diverse set of options for async programming. This client library can be used with any async runtime out of the box, such as async-std and tokio.
  -The sync interface provided by this library is implemented as just a thin wrapper around its async interface. Those two interface styles look very similar, and you're free to choose whichever works best for your application.
  +The async interface provided by this library is implemented as just a thin wrapper around its sync interface. Those two interface styles look very similar, and you're free to choose whichever works best for your application.
  ## Features
  The following is a list of features currently supported and planned for the near future.
  