Add screenshot stub how to launch and add screengrab to toctree

source/2/2.3/2.3.3/screenshot.rst

@@ -0,0 +1,12 @@
+Chapter 2.3.3 Screenshot
+========================
+
+Screenshot is a program to take screenshots.
+
+Version
+-------
+Lubuntu ships with version 0.7.0 of screenshot. 
+
+How to Launch
+-------------
+To launch screenshot from the menu -> Grapics -> Screenshot or run lximage-qt -s from the command line.

source/2/2.3/Graphics_Applications.rst

@@ -6,4 +6,6 @@ Chapter 2.2.3 Graphics Applications
   :titlesonly:
 
   2.3.1/lximage
+  2.3.2/screengrab
+  2.3.3/screenshot
   2.3.4/Skanlite