In new content addressable model, image no longer
have virtual size column, it is now 'size'. So we
need to update related docs about them.
Signed-off-by: Kai Qiang Wu(Kennan) <wkqwu@cn.ibm.com>
Fixing the links
Updating with Seb's comments
Adding weight
Fixing the engine aliases
Updating after Arun pushed
Removing empty file
Signed-off-by: Mary Anthony <mary@docker.com>