fix documentation inacuracy
fix documentation inacuracy

BUG=aomedia:573

Change-Id: I3989375bf97e344b422953833e853e66dcb07b23

GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom