Change static.rust-lang.org to doc.rust-lang.org

The new documentation site has shorter urls, gzip'd content, and index.html
redirecting functionality.

src/libregex/lib.rs

@@ -359,7 +359,7 @@
 #![license = "MIT/ASL2"]
 #![doc(html_logo_url = "http://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
        html_favicon_url = "http://www.rust-lang.org/favicon.ico",
-       html_root_url = "http://static.rust-lang.org/doc/master")]
+       html_root_url = "http://doc.rust-lang.org/")]
 
 #![feature(macro_rules, phase)]
 #![deny(missing_doc, deprecated_owned_vector)]