zfs test_maximum_size_enforced: add a comment explaining maximum_size value
zfs test_maximum_size_enforced: add a comment explaining maximum_size value

AndyHuu/flocker,adamtheturtle/flocker,AndyHuu/flocker,w4ngyi/flocker,hackday-profilers/flocker,achanda/flocker,agonzalezro/flocker,w4ngyi/flocker,1d4Nf6/flocker,moypray/flocker,Azulinho/flocker,wallnerryan/flocker-profiles,adamtheturtle/flocker,moypray/flocker,wallnerryan/flocker-profiles,1d4Nf6/flocker,mbrukman/flocker,mbrukman/flocker,w4ngyi/flocker,Azulinho/flocker,achanda/flocker,hackday-profilers/flocker,hackday-profilers/flocker,AndyHuu/flocker,Azulinho/flocker,wallnerryan/flocker-profiles,1d4Nf6/flocker,agonzalezro/flocker,moypray/flocker,adamtheturtle/flocker,agonzalezro/flocker,achanda/flocker,mbrukman/flocker