printf(1): Clarify that \OOO produces a byte, different %b escape sequences.

Octal escape sequences are expanded to bytes, not characters, and multiple
are required for a multibyte character.

The valid escape sequences in %b strings are slightly different from the
escape sequences in the format string.

usr.bin/printf/printf.1

@@ -35,7 +35,7 @@
 .\"	@(#)printf.1	8.1 (Berkeley) 6/6/93
 .\" $FreeBSD$
 .\"
-.Dd April 14, 2005
+.Dd September 5, 2010
 .Dt PRINTF 1
 .Os
 .Sh NAME
@@ -109,12 +109,13 @@ Write a <single quote> character.
 .It Cm \e\e
 Write a backslash character.
 .It Cm \e Ns Ar num
-.It Cm \e0 Ns Ar num
-Write an 8-bit character whose
-.Tn ASCII
+Write a byte whose
 value is the 1-, 2-, or 3-digit
 octal number
 .Ar num .
+Multibyte characters can be constructed using multiple
+.Cm \e Ns Ar num
+sequences.
 .El
 .Pp
 Each format specification is introduced by the percent character
@@ -289,6 +290,11 @@ As for
 .Cm s ,
 but interpret character escapes in backslash notation in the string
 .Ar argument .
+The permitted escape sequences are slightly different in that
+octal escapes are
+.Cm \e0 Ns Ar num
+instead of
+.Cm \e Ns Ar num .
 .It Cm \&%
 Print a `%'; no argument is used.
 .El