Thanks @jgkim 
I have applied a number of logos to the sub-categories in this forum.
As mentioned elsewhere we need to apply the CSS so that the icons in the at the top Category level don’t appear ridiculously large. I added the Open Spending logo to the Open Spending category but it looked so big I removed it.
Alternately, the logos need to be resized down. The tools I have access to don’t do this very well 