man: document LoaderConfigConsoleMode

The variable was introduced with systemd v250 although it went
completely undocumented, even though sd-boot will honour and print it
separately (from the loader.conf one) in the boot help screen.

Document it in the systemd-boot and hint about it in loader.conf manual
pages.

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>

man/loader.conf.xml

@@ -142,9 +142,12 @@
       <varlistentry>
         <term>console-mode</term>
 
-        <listitem><para>This option configures the resolution of the console. Takes a
-        number or one of the special values listed below. The following values may be
-        used:</para>
+        <listitem><para>This option configures the resolution of the console. This may be changed in
+        the boot menu itself and will be stored as an EFI variable in that case, overriding this
+        option.</para>
+
+        <para>Takes a number or one of the special values listed below. The following
+        values may be used:</para>
 
         <variablelist>
           <varlistentry>

man/systemd-boot.xml

@@ -416,6 +416,15 @@
         <xi:include href="version-info.xml" xpointer="v240"/></listitem>
       </varlistentry>
 
+      <varlistentry>
+        <term><varname>LoaderConfigConsoleMode</varname></term>
+        <listitem><para>The numerical menu console mode. Read by the boot loader. <varname>LoaderConfigConsoleMode</varname>
+        is maintained persistently. <varname>LoaderConfigConsoleMode</varname> may be manipulated with the
+        <keycap>r</keycap>/<keycap>R</keycap> keys, see above.</para>
+
+        <xi:include href="version-info.xml" xpointer="v250"/></listitem>
+      </varlistentry>
+
       <varlistentry>
         <term><varname>LoaderDevicePartUUID</varname></term>