tunefs.8/newfs.8: Specify unit of the avgfilesize parameter

The avgfilesize description does not say what the unit is (sectors,
blocks, bytes). Extend the description to mention that this parameter is
in bytes.

PR:                     298705
Event:	                Oslo Hackathon 2026
Differential Revision:  https://reviews.freebsd.org/D61047

sbin/newfs/newfs.8

@@ -166,7 +166,7 @@ and
 .\" of the first backup superblock on the fsck_ffs.8 manual page.
 The default is 4096 bytes.
 .It Fl g Ar avgfilesize
-The expected average file size for the file system.
+The expected average file size for the file system in bytes.
 .It Fl h Ar avgfpdir
 The expected average number of files per directory on the file system.
 .It Fl i Ar bytes

sbin/tunefs/tunefs.8

@@ -25,7 +25,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd March 20, 2026
+.Dd October 30, 2026
 .Dt TUNEFS 8
 .Os
 .Sh NAME
@@ -89,7 +89,7 @@ in a cylinder group before seeking elsewhere.
 For file systems with exclusively large files,
 this parameter should be set higher.
 .It Fl f Ar avgfilesize
-Specify the expected average file size.
+Specify the expected average file size in bytes.
 .It Fl j Cm enable | disable
 Turn on/off soft updates journaling.
 Enabling soft updates journaling implies enabling soft updates and is