doc: Update more docstrings to have one sentence summary as first line. Reviewed plot/ and gui/ in scripts directory. * scripts/gui/errordlg.m, scripts/gui/helpdlg.m, scripts/gui/inputdlg.m, scripts/gui/listdlg.m, scripts/gui/msgbox.m, scripts/gui/private/__get_funcname__.m, scripts/gui/private/__uiobject_split_args__.m, scripts/gui/questdlg.m, scripts/gui/uigetdir.m, scripts/gui/uigetfile.m, scripts/gui/uiwait.m, scripts/gui/waitbar.m, scripts/gui/warndlg.m, scripts/plot/appearance/annotation.m, scripts/plot/appearance/axis.m, scripts/plot/appearance/box.m, scripts/plot/appearance/caxis.m, scripts/plot/appearance/datetick.m, scripts/plot/appearance/hidden.m, scripts/plot/appearance/legend.m, scripts/plot/appearance/xlim.m, scripts/plot/appearance/ylim.m, scripts/plot/appearance/zlim.m, scripts/plot/draw/area.m, scripts/plot/draw/comet.m, scripts/plot/draw/comet3.m, scripts/plot/draw/contour.m, scripts/plot/draw/contourf.m, scripts/plot/draw/isocolors.m, scripts/plot/draw/isonormals.m, scripts/plot/draw/isosurface.m, scripts/plot/draw/plotmatrix.m, scripts/plot/draw/quiver.m, scripts/plot/draw/quiver3.m, scripts/plot/draw/ribbon.m, scripts/plot/draw/semilogxerr.m, scripts/plot/draw/semilogyerr.m, scripts/plot/draw/sphere.m, scripts/plot/draw/surfl.m, scripts/plot/draw/tetramesh.m, scripts/plot/util/allchild.m, scripts/plot/util/ancestor.m, scripts/plot/util/axes.m, scripts/plot/util/colstyle.m, scripts/plot/util/frame2im.m, scripts/plot/util/gnuplot_binary.in, scripts/plot/util/hgsave.m, scripts/plot/util/im2frame.m, scripts/plot/util/isaxes.m, scripts/plot/util/isfigure.m, scripts/plot/util/linkaxes.m, scripts/plot/util/ndgrid.m, scripts/plot/util/pan.m, scripts/plot/util/print.m, scripts/plot/util/printd.m, scripts/plot/util/private/__add_default_menu__.m, scripts/plot/util/rotate.m, scripts/plot/util/rotate3d.m, scripts/plot/util/saveas.m, scripts/plot/util/struct2hdl.m, scripts/plot/util/subplot.m, scripts/plot/util/zoom.m: Update more docstrings to have one sentence summary as first line.

--- a/scripts/plot/draw/plotmatrix.m
+++ b/scripts/plot/draw/plotmatrix.m
@@ -24,14 +24,14 @@
 ## @deftypefnx {Function File} {[@var{h}, @var{ax}, @var{bigax}, @var{p}, @var{pax}] =} plotmatrix (@dots{})
 ## Scatter plot of the columns of one matrix against another.
 ##
-## Given the arguments @var{x} and @var{y}, that have a matching number of
+## Given the arguments @var{x} and @var{y} that have a matching number of
 ## rows, @code{plotmatrix} plots a set of axes corresponding to
 ##
 ## @example
 ## plot (@var{x}(:, i), @var{y}(:, j))
 ## @end example
 ##
-## Given a single argument @var{x} this is equivalent to
+## When called with a single argument @var{x} this is equivalent to
 ##
 ## @example
 ## plotmatrix (@var{x}, @var{x})
@@ -49,11 +49,14 @@
 ##
 ## The optional return value @var{h} provides handles to the individual
 ## graphics objects in the scatter plots, whereas @var{ax} returns the
-## handles to the scatter plot axis objects.  @var{bigax} is a hidden
-## axis object that surrounds the other axes, such that the commands
-## @code{xlabel}, @code{title}, etc., will be associated with this hidden
-## axis.  Finally, @var{p} returns the graphics objects associated with
-## the histogram and @var{pax} the corresponding axes objects.
+## handles to the scatter plot axis objects.
+##
+## @var{bigax} is a hidden axis object that surrounds the other axes, such
+## that the commands @code{xlabel}, @code{title}, etc., will be associated
+## with this hidden axis.
+##
+## Finally, @var{p} returns the graphics objects associated with the histogram
+## and @var{pax} the corresponding axes objects.
 ##
 ## Example:
 ##