README - show .create with default options - jsondiffpatch.create({})

[floer32]

If you do jsondiffpatch.create() (with no options argument), you get a confusing error: TypeError: Cannot read property 'processor' of undefined. This doesn't indicate the problem that create expects an empty options object, {}. Instead of adding handling or an error, for that case, I think the README is a fine solution.

README should mention this. jsondiffpatch does have sane defaults already, except for this one pesky case.

Resolves #266