Fix documentation links

Closes rust-lang#216

README.md

@@ -6,8 +6,8 @@ A Rust library providing a lightweight logging *facade*.
 [![Build Status](https://travis-ci.org/rust-lang-nursery/log.svg?branch=master)](https://travis-ci.org/rust-lang-nursery/log)
 [![Build status](https://ci.appveyor.com/api/projects/status/nopdjmmjt45xcrki?svg=true)](https://ci.appveyor.com/project/alexcrichton/log)
 
-* [`log` documentation](https://doc.rust-lang.org/log)
-* [`env_logger` documentation](https://doc.rust-lang.org/log/env_logger)
+* [`log` documentation](https://docs.rs/log)
+* [`env_logger` documentation](https://docs.rs/env_logger)
 
 A logging facade provides a single logging API that abstracts over the actual
 logging implementation. Libraries can use the logging API provided by this