doc: Document expect_value().
doc: Document expect_value().

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