man/localtime: document default timezone

This explicitly documents the default `UTC` timezone which is used
by systemd and (other softwares) when `/etc/localtime` is not present.

Ref: https://github.com/systemd/systemd/blob/v247/src/basic/time-util.c#L1460-L1469

diff --git a/man/localtime.xml b/man/localtime.xml
index 73c1b8e5a30f95a6419fabb8ac191c88a8684cde..e486474c446b841311017ed09fe7022dca5abe72 100644 (file)
--- a/man/localtime.xml
+++ b/man/localtime.xml
@@ -41,6 +41,9 @@
     symlink target name of <filename>/etc/localtime</filename>, this
     file may not be a normal file or hardlink.</para>
 
+    <para>If <filename>/etc/localtime</filename> is missing, the
+    default <literal>UTC</literal> timezone is used.</para>
+
     <para>The timezone may be overridden for individual programs by
     using the <varname>$TZ</varname> environment variable. See
     <citerefentry project='man-pages'><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>