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

shepmaster/rand,bhickey/rand,ebfull/rand,GrahamDennis/rand,retep998/rand,arthurprs/rand,achanda/rand,bluss/rand,waynenilsen/rand,huonw/rand