consolidating /images and /docs/images folders

[nate-double-u]

Moving images in the root images folder to the /docs/images folder.

I had considered moving this image into the /analyses folder where it is referenced, but as only one analysis actually has an image, I think it's probably better to keep all the images in one place.

contributes to #247

[nate-double-u]

In future, this sort of information would be better represented in a table, but since it's referring to an artifact generated in another system I think it's fine as is.