add a minor clarification in comment
add a minor clarification in comment

Change-Id: I7320074ff7bd95d833cba8afb04fcc0730392f1e

luctrudeau/aom,smarter/aom,smarter/aom,luctrudeau/aom,smarter/aom,luctrudeau/aom,smarter/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,luctrudeau/aom,GrokImageCompression/aom,smarter/aom,GrokImageCompression/aom,GrokImageCompression/aom,luctrudeau/aom,luctrudeau/aom,smarter/aom