Document the 'show bio' command added in 2009.

While here also reword 'show buffer' to have an 'addr' argument and to
match other struct documentation.

MFC after:	1 week
Sponsored by:	EMC / Isilon Storage Division

1 files changed, 17 insertions, 10 deletions

diff --git a/share/man/man4/ddb.4 b/share/man/man4/ddb.4
index 01f5135..2ec40cd 100644
--- a/share/man/man4/ddb.4
+++ b/share/man/man4/ddb.4
@@ -60,7 +60,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd September 30, 2013
+.Dd July 15, 2014
 .Dt DDB 4
 .Os
 .Sh NAME
@@ -572,17 +572,24 @@ Dump data about APIC IDT vector mappings.
 Show breakpoints set with the "break" command.
 .\"
 .Pp
-.It Ic show Cm buffer
-Show buffer structure of
+.It Ic show Cm bio Ar addr
+Show information about the bio structure
+.Vt struct bio
+present at
+.Ar addr .
+See the
+.Pa sys/bio.h
+header file for more details on the exact meaning of the structure fields.
+.\"
+.Pp
+.It Ic show Cm buffer Ar addr
+Show information about the buf structure
 .Vt struct buf
-type.
-Such a structure is used within the
-.Fx
-kernel for the I/O subsystem
-implementation.
-For an exact interpretation of the output, please see the
+present at
+.Ar addr .
+See the
 .Pa sys/buf.h
-header file.
+header file for more details on the exact meaning of the structure fields.
 .\"
 .Pp
 .It Ic show Cm cbstat