Rewrite page(2) references to page(3).

Add description of new libmach.

man/man3/cachechars.3

@@ -181,7 +181,7 @@ The
 and
 .LR ascent
 fields of Font are described in
-.IR graphics (2).
+.IR graphics (3).
 .L Sub
 contains
 .L nsub
@@ -302,12 +302,12 @@ for replacement when the cache is full.
 .SH SOURCE
 .B /sys/src/libdraw
 .SH SEE ALSO
-.IR graphics (2),
-.IR allocimage (2),
-.IR draw (2),
-.IR subfont (2),
+.IR graphics (3),
+.IR allocimage (3),
+.IR draw (3),
+.IR subfont (3),
 .IR image (6),
 .IR font (6)
 .SH DIAGNOSTICS
 All of the functions use the graphics error function (see
-.IR graphics (2)).
+.IR graphics (3)).