Add docs.rs and appveyor badges

README.md

@@ -6,7 +6,9 @@ with a simple interface while also exposing iterators for items of every level
 in a PBF file.
 
 [![Build Status](https://travis-ci.org/b-r-u/osmpbf.svg?branch=master)](https://travis-ci.org/b-r-u/osmpbf)
-[![](https://img.shields.io/crates/v/osmpbf.svg)](https://crates.io/crates/osmpbf)
+[![Build status](https://ci.appveyor.com/api/projects/status/1ct6i2gjsak8tgyy?svg=true)](https://ci.appveyor.com/project/b-r-u/osmpbf)
+[![Crates.io](https://img.shields.io/crates/v/osmpbf.svg)](https://crates.io/crates/osmpbf)
+[![Documentation](https://docs.rs/osmpbf/badge.svg)](https://docs.rs/osmpbf)
 
 ## Usage