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

gnanderson/go,dsriram/golang,apparentlymart/golang,dsriram/golang,gnanderson/go,gnanderson/go,tv42/old-go,pombredanne/go-deleteme,tv42/old-go,pombredanne/go-deleteme,apparentlymart/golang,pombredanne/go-deleteme,apparentlymart/golang,tv42/old-go,gnanderson/go,apparentlymart/golang,tv42/old-go,dsriram/golang,tv42/old-go,apparentlymart/golang,pombredanne/go-deleteme,tv42/old-go,dsriram/golang,gnanderson/go,apparentlymart/golang,pombredanne/go-deleteme,gnanderson/go,tv42/old-go,pombredanne/go-deleteme,dsriram/golang,apparentlymart/golang,dsriram/golang,pombredanne/go-deleteme,gnanderson/go,dsriram/golang