Update quick start instructions

[Aleksey Shipilev]

On 12/5/18 2:47 PM, Felix Riemann wrote:
> I just realized I had been running jcstress 0.1.1 for ages, because I used
> https://wiki.openjdk.java.net/display/CodeTools/jcstress to setup the project. Maybe the page can
> be updated to get people to use the recent version right from the start?

Oops. Thanks for reporting! Actually, we can drop -DarchetypeVersion completely, and let Maven
figure out the latest one automatically. Updated the page accordingly.

Thanks,
-Aleksey