quantity.example: language in the comments

+quantity/example.m

-%% example.m gives an overview of basic mathematical operations 
-% using quantity.Discrete class
+%% example.m gives an overview of basic mathematical operations using the quantity.Discrete class
 
 %% Create a new quantity
 % First, we want to create a scalar function a(z) = 1 + z that depends on a spatial variable 
@@ -160,21 +159,22 @@ y = x + cumInt(K*x.subs("z", "zeta"), "zeta", 0, "z");
 y.plot();
 
 %% plotting of quantities
-% As have been shown, quantities can be displayed by the plot method. For each quantity a new window
-% is opened and each entry of a matrix valued quantity is plotted into a own subplot. To specifiy
-% which figure should be used for a plot the optional name-value-pair argument "fig" can be used:
+% As has been shown, quantities can be displayed by the plot method. By default, for each quantity a
+% new window is opened and each entry of a matrix valued quantity is plotted into a own subplot. 
+% To specifiy which figure should be used for a plot the optional name-value pair argument "fig" can 
+% be used. For instance, the following line will plot a quantity into figure number 1. 
 a.plot("fig", 1)
-% will plot quantity a into figure 1. If a second quantity should be plotted into the same window,
-% the optional name-value-pair "hold" can be used:
+% If a second quantity should be plotted into the same subplot afterwards, the name-value pair 
+% "hold" can be used. For instance, the following plots the first derivative a_dz of a into the same
+% subplot:
 a_dz.plot("fig", 1, "hold", true)
-% will plot first derivative of a into the same figure. 
-% To use the subplot to display different quantities, use the "currentFigure" optional
-% name-value-argument:
+% To display different quantities in different subplots, use "subplot()" and the "currentFigure"
+% name-value argument:
 figure(1); clf;
 subplot(211);
 c.plot("currentFigure", true);
-% with this argument combined with the "hold" option, all entries of a matrix valued quantity can be
-% composed into one axis:
+% With "currentFigure", true combined with the "hold" option, all entries of a matrix valued 
+% quantity are composed into one axis:
 subplot(212);
 aaa.plot("currentFigure", true, "hold", true)