Add in screenshots for office applications written so far. (#32)

* fix path to gnome-mpv

* fix document viewer index

* start xfburn

* fix file name capitilization

* cleanup bad filename.

* add tweaking your desktop chapter blurb.

* add screenshots for pavucontrol and xfburn

* add screenshot for abiword and evince

* add screenshot for simple-scan

source/3/3.2/3.2.1/abiword.rst

@@ -20,6 +20,11 @@ Version
 -------
 Lubuntu ships with version 3.0.2
 
+Screenshot
+----------
+.. image:: abiword.png
+   :width: 80%
+
 Useage
 ------
 To use abiword you type your document into the the window. You can save your document by clicking the icon that looks like a disk with an icon pointing down on it on the toolbar. If you wish to open this document again after say you shutdown your computer click the button that looks like a folder and a dialog will pop up to find the document. You can check your spelling with the button that says abc with a green squiggly line underneath it. To print press the icon that uses a printer with a down arrow underneath it. 

source/3/3.2/3.2.3/document_viewer.rst

@@ -9,10 +9,14 @@ Version
 -------
 Lubuntu ships with version 3.28
 
-Useage/screenshots
-------------------
+Useage
+------
 To scroll through multiple pages use either the scrollwheel on the mouse or on a touchpad. To go to a specific page in the document in the upper left corner next to the evince icon by default there is a box that says 1 of 6 to jump to that page.
 
+Screenshot
+----------
+  .. image:: document_viewer.png
+     :width: 80%
 
 How to Launch
 -------------

source/3/3.2/3.2.4/simple_scan.rst

@@ -12,6 +12,12 @@ Useage
 ------
 To use simple scan have your scanner turned on to start. To scan a page press the scan button. If you need to rotate a page to the left or the right you can easily use the arrows to the left or the right. If you are saving just one picture you can save it now as a jpeg. If you want to scan a multi-page document you can load the next page in the scanner now and the press scan and repeat this for the remaining pages. When you are finished press the save button and save the file as a pdf. 
 
+Screenshot
+----------
+ .. image:: simple_scan.png
+   :width: 80%
+
+
 How to Launch
 -------------
 To launch Simple Scan in the main menu under graphics click on the icon that looks like a glass sheet with a piece of paper and a beam of light across it like you would if you had the top up on a flatbed scanner looking down. Alternatively you can run simple-scan from the command line.