doc: Document assert_memory_not_equal().
doc: Document assert_memory_not_equal().

jamesmunns/CMocka,JonathonReinhart/cmocka,jschmidlapp/cmocka,clibs/cmocka,lsjostro/cmocka,dsch/cmocka,tyc/cmocka,nuumio/cmocka,JonathonReinhart/cmocka,wingyplus/cmocka,Odie/cmocka,chadversary/cmocka,jhrozek/cmocka,aleksandr-vin/cmock,jamesmunns/CMocka,VladimirTyrin/cmocka,lsjostro/cmocka,linuxmaniac/cmocka,tyc/cmocka,dsch/cmocka,linuxmaniac/cmocka,nuumio/cmocka,Odie/cmocka,tyc/cmocka,Odie/cmocka,chadversary/cmocka,jhrozek/cmocka,VladimirTyrin/cmocka,wingyplus/cmocka,jschmidlapp/cmocka,aleksandr-vin/cmock,jschmidlapp/cmocka,nuumio/cmocka,jhrozek/cmocka,clibs/cmocka