flag: fix error in documentation example. Fixes issue 1615. This time for sure.
flag: fix error in documentation example.
Fixes issue 1615.
This time for sure.

R=rsc, gri
CC=golang-dev
http://codereview.appspot.com/4275079

sanjosh/sanjos100-tipc,glycerine/jeaten-go-arrayof-structof,scirelli/scirelli-go,sanjosh/sanjos100-tipc,bryanxu/go-zh,mhennings/marcohennings-go,d0f/go-zh,npe9/noahevans-go9,sanjosh/sanjos100-tipc,rdp/rogerpack2005-golang,rdp/rogerpack2005-golang,d0f/go-zh,webfd/go-zh,sanjosh/sanjos100-tipc,sanjosh/sanjos100-tipc,npe9/noahevans-go9,npe9/noahevans-go9,mhennings/marcohennings-go,webfd/go-zh,webfd/go-zh,Triskite/willstone-goclone,d0f/go-zh,mhennings/marcohennings-go,rflanagan/reginaldflanagan-project1,glycerine/jeaten-go-arrayof-structof,npe9/noahevans-go9,npe9/noahevans-go9,webfd/go-zh,rflanagan/reginaldflanagan-project1,rdp/rogerpack2005-golang,scirelli/scirelli-go,Triskite/willstone-goclone,webfd/go-zh,mhennings/marcohennings-go,scirelli/scirelli-go,rdp/rogerpack2005-golang,glycerine/jeaten-go-arrayof-structof,scirelli/scirelli-go,mhennings/marcohennings-go,glycerine/jeaten-go-arrayof-structof,d0f/go-zh,scirelli/scirelli-go,Triskite/willstone-goclone,bryanxu/go-zh,rdp/rogerpack2005-golang,npe9/noahevans-go9,rdp/rogerpack2005-golang,scirelli/scirelli-go,d0f/go-zh,Triskite/willstone-goclone,Triskite/willstone-goclone,sanjosh/sanjos100-tipc,Triskite/willstone-goclone,glycerine/jeaten-go-arrayof-structof,webfd/go-zh,d0f/go-zh,rflanagan/reginaldflanagan-project1,mhennings/marcohennings-go,mhennings/marcohennings-go,bryanxu/go-zh,rflanagan/reginaldflanagan-project1,rflanagan/reginaldflanagan-project1,scirelli/scirelli-go,bryanxu/go-zh,webfd/go-zh,Triskite/willstone-goclone,rdp/rogerpack2005-golang,npe9/noahevans-go9,npe9/noahevans-go9,scirelli/scirelli-go,d0f/go-zh,bryanxu/go-zh,rflanagan/reginaldflanagan-project1,Triskite/willstone-goclone,rflanagan/reginaldflanagan-project1,glycerine/jeaten-go-arrayof-structof,d0f/go-zh,sanjosh/sanjos100-tipc,bryanxu/go-zh,glycerine/jeaten-go-arrayof-structof,bryanxu/go-zh,glycerine/jeaten-go-arrayof-structof,bryanxu/go-zh,webfd/go-zh,mhennings/marcohennings-go,rflanagan/reginaldflanagan-project1,sanjosh/sanjos100-tipc,rdp/rogerpack2005-golang