doc/articles/c_go_cgo.html: correct "C" comment to mention #cgo
doc/articles/c_go_cgo.html: correct "C" comment to mention #cgo

Also fix invalid apostrophe characters.

R=r, gri, adg
CC=golang-dev
http://codereview.appspot.com/5874058

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