misc/cstring.h: fix documentation for b_cstring_memchr()
misc/cstring.h: fix documentation for b_cstring_memchr()

DavidCox1979/badvpn,DavidCox1979/badvpn,DavidCox1979/badvpn,DavidCox1979/badvpn,DavidCox1979/badvpn