Documentation on chooser with batches

[solonrice]

I spent quite a while trying to figure out why the image chooser only showed 1 image. Then I realized there was a setting in the latent image node that has "batch_size", which must be something other than 1. Perhaps an expert would have known that intuitively, but since the main point of this hinges on that being something other than 1, I was thinking there should be documentation around it in the README.