message: chore(README): remove AppVeyor badge
diff: # [hyper](https://hyper.rs)
  [![Travis Build Status](https://travis-ci.org/hyperium/hyper.svg?branch=master)](https://travis-ci.org/hyperium/hyper)
  -[![Appveyor Build status](https://ci.appveyor.com/api/projects/status/tb0n55fjs5tohdfo/branch/master?svg=true)](https://ci.appveyor.com/project/seanmonstar/hyper)
  [![Coverage Status](https://coveralls.io/repos/hyperium/hyper/badge.svg?branch=master)](https://coveralls.io/r/hyperium/hyper?branch=master)
  [![MIT licensed](https://img.shields.io/badge/license-MIT-blue.svg)](./LICENSE)
  [![crates.io](https://meritbadge.herokuapp.com/hyper)](https://crates.io/crates/hyper)
  [![Released API docs](https://docs.rs/hyper/badge.svg)](https://docs.rs/hyper)
  -[![Master API docs](https://img.shields.io/badge/docs-master-green.svg)](https://hyper.rs/hyper/master/)
  A **fast** and **correct** HTTP implementation for Rust.
  