add AMD-specific instructions to README

[benatkin]

It would be nice to have a little note in the README, and perhaps an example.

[jrburke]

I'm a bit hesitant to do that, as I want to minimize the changes we do the backbone tree. I also assumed that people coming to this fork know what it is for, although maybe that is not true.

[mcgwiz]

FYI, you could change the Description and Website of the repository to something specific to this fork (mouseover either to reveal an Edit button). Visitors will still understand the context of this fork since Github always displays a link back to the originating repo.

[jrburke]

@mcgwiz thanks for the suggestion, I updated that part in the github UI to mention this is an AMD-enabled fork of backbone. I suppose we could point the URL in that section to a "how to" on a wiki page, but I do not have the bandwidth at the moment to do that. If someone wants to make one, maybe use the wiki in this fork, then I can update the description section.

[benatkin]

Much better idea than I had, Mike. Thanks! And the wiki would make it better still. :)