Enable data-sdb-width and data-sdb-height for customized dimension when using customized image in data attribution

I found the data-sdb-image is must more useful when I can set the dimension alongside the image url. In some cases the customized image does not share exactly the same dimension of the default image. 

Updated the example.html with last example on how this works.

Signed-off-by: Thomas Seng Hin Mak <makzan@gmail.com>