tune2fs.8: Document that the device can be specified via LABEL= or UUID=

Addresses-Debian-Bug: #580236

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/misc/tune2fs.8.in b/misc/tune2fs.8.in
index dffe76d..2f9db81 100644
--- a/misc/tune2fs.8.in
+++ b/misc/tune2fs.8.in
@@ -96,6 +96,12 @@
 program, or by using the
 .BR dumpe2fs (8)
 program.
+.PP
+The
+.I device
+specifer can either be a filename (i.e., /dev/sda1), or a LABEL or UUID
+specifer: "\fBLABEL=\fIvolume-name\fR" or "\fBUUID=\fIuuid\fR".  (i.e.,
+LABEL=home or UUID=e40486c6-84d5-4f2f-b99c-032281799c9d).
 .SH OPTIONS
 .TP
 .BI \-c " max-mount-counts"