Update README.md with correct installation link
# Install instructions
To install and run Urbit please follow the instructions at
-[urbit.org/docs/using/install](http://urbit.org/docs/using/install). Packages
+[urbit.org/docs/getting-started/](urbit.org/docs/getting-started). Packages
and source tarballs are available there. You'll be on the live network in a few
minutes.
