documentation - invalid url

[maxfiedler1988 at gmail.com]

Hello,

I'm reading through the handbook online and just realized there is an 
invalid url in chapter "2.4.1. Booting on i386™ and amd64"; the url to 
the Plop Boot Manager is no longer 
http://www.plop.at/en/bootmanager.html but now 
http://www.plop.at/en/bootmanagers.html

Sincerely

Max Fiedler