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

Add description of new libmach.

man/man3/bio.3

@@ -90,7 +90,7 @@ for mode
 or creates for mode
 .BR OWRITE .
 It calls
-.IR malloc (2)
+.IR malloc (3)
 to allocate a buffer.
 .PP
 .I Binit
@@ -159,7 +159,7 @@ of the most recent string returned by
 .PP
 .I Brdstr
 returns a
-.IR malloc (2)-allocated
+.IR malloc (3)-allocated
 buffer containing the next line of input delimited by
 .IR delim ,
 terminated by a NUL (0) byte.
@@ -211,7 +211,7 @@ may back up a maximum of five bytes.
 uses
 .I charstod
 (see
-.IR atof (2))
+.IR atof (3))
 and
 .I Bgetc
 to read the formatted
@@ -232,7 +232,7 @@ and a negative value is returned if a read error occurred.
 .PP
 .I Bseek
 applies
-.IR seek (2)
+.IR seek (3)
 to
 .IR bp .
 It returns the new file offset.
@@ -264,7 +264,7 @@ on the output stream.
 .PP
 .I Bprint
 is a buffered interface to
-.IR print (2).
+.IR print (3).
 If this causes a
 .IR write
 to occur and there is an error,
@@ -309,9 +309,9 @@ written.
 .SH SOURCE
 .B /sys/src/libbio
 .SH SEE ALSO
-.IR open (2),
-.IR print (2),
-.IR exits (2),
+.IR open (3),
+.IR print (3),
+.IR exits (3),
 .IR utf (6),
 .SH DIAGNOSTICS
 .I Bio