man: ip: add -h[uman-readable] option

Since 'ip help' lists it, it should be described in ip.8 as well.

Signed-off-by: Phil Sutter <phil@nwl.cc>
diff --git a/man/man8/ip.8 b/man/man8/ip.8
index 9da086d..e6c2b32 100644
--- a/man/man8/ip.8
+++ b/man/man8/ip.8
@@ -27,6 +27,7 @@
 .ti -8
 .IR OPTIONS " := { "
 \fB\-V\fR[\fIersion\fR] |
+\fB\-h\fR[\fIuman-readable\fR] |
 \fB\-s\fR[\fItatistics\fR] |
 \fB\-r\fR[\fIesolve\fR] |
 \fB\-f\fR[\fIamily\fR] {
@@ -46,6 +47,10 @@
 utility and exit.
 
 .TP
+.BR "\-h", " \-human", " \-human-readable"
+output statistics with human readable values followed by suffix.
+
+.TP
 .BR "\-b", " \-batch " <FILENAME>
 Read commands from provided file or standard input and invoke them.
 First failure will cause termination of ip.