Website section for multi-arch specifics

[rbowen]

It would be helpful, now that we are supporting multiple architectures, to have a page/section of the website talking about multi-arch and whatever details/differences there are.

@pmkovar should this go under the "use" section?

[pmkovar]

@pmkovar should this go under the "use" section?

@rbowen I think so. It sounds more fitting than "contribute".