Never new Rust by Example existed until today actually! You really should link to it somewhere more prominent. I'm fairly far along, but would have loved the example book had I know about it sooner.
We do link it from http://doc.rust-lang.org/ , but I guess that still says community...
It actually took me a while to find the link there just now. I don't think "External Documentation" really imparts the right meaning. Perhaps something like "Other Guides and Resources" would make more sense?