README mentions "script/server" etc, should be "rails server"

The README file that goes into generated apps mentions "script/server", "script/console", "script/dbconsole" and "script/generate". These commands don't work in Rails 3.

The attached patch changes them to "rails server" etc.

There is a bunch more that could be done: there are mentions of "script/server" in other files, mostly in guides; there are two almost-but-not-quite-identical README files (railties/README, railties/lib/generators/rails/app/templates/README) that probably started out the same and drifted apart; the README is probably inaccurate in many respects.

I figure changing the broken "script/server" etc in the README can stand on its own, though. If I or someone else finds more time, they can work on the rest.