website: 404 link

[Fiyorin]

the link to the readme file on the frontpage of the www.rust-lang.org website leads to a 404 error: https://github.com/mozilla/rust/blob/release-0.3.1/RELEASES.txt

[brson]

This is a symptom of #3541

[brson]

I've removed the link, since there isn't a 0.3.1-specific README to link to any way.