man: Remove description of DRM specific mode-options from weston.ini.man

The weston.ini.man describes the mode-formats that a user can specify
for selecting a video mode. The DRM specific examples are already
provided in weston-drm.man, so this inofrmation is redundant and can
be removed.

This patch removes the DRM specific mode option details from the
description of mode configuration in weston.ini.man.
A pointer to weston-drm.man is given, which has complete information
about the mode-format options supported by DRM backend.

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
diff --git a/man/weston.ini.man b/man/weston.ini.man
index 02c9b03..199b465 100644
--- a/man/weston.ini.man
+++ b/man/weston.ini.man
@@ -406,31 +406,11 @@
 sets the output mode (string). The mode parameter is handled differently
 depending on the backend. On the X11 backend, it just sets the WIDTHxHEIGHT of
 the weston window.
-The DRM backend accepts different modes:
-.PP
-.RS 10
-.nf
-.BR "WIDTHxHEIGHT    " "Resolution size width and height in pixels"
-.BR "preferred       " "Uses the preferred mode"
-.BR "current         " "Uses the current crt controller mode"
-.BR "off             " "Disables the output"
-.fi
-.RE
-.RS
-.PP
-Optionally, a user may specify a modeline, such as:
-.PP
-.nf
-.in +4n
-.nf
-173.00  1920 2048 2248 2576  1080 1083 1088 1120 -hsync +vsync
-.fi
-.in
-.PP
-It consists of the refresh rate in Hz, horizontal and vertical resolution,
-options for horizontal and vertical synchronisation. The program
-.B "cvt(1)"
-can provide suitable modeline string.
+The DRM backend accepts different modes, along with an option of a modeline string.
+
+See
+.B "weston-drm(7)"
+for examples of modes-formats supported by DRM backend.
 .RE
 .TP 7
 .BI "transform=" normal