Fixed the README with respect extern crate.

ereichert · ereichert · commit b8852953f3fc · 2015-03-28T12:46:50.000-04:00
diff --git a/README.md b/README.md
@@ -19,5 +19,5 @@ rustc-serialize = "0.3"
 and this to your crate root:
 
 ```rust
-extern crate "rustc-serialize" as rustc_serialize;
+extern crate rustc_serialize;
 ```
