Add information about software sources and updates

Package_Management/Graphical_Tools/index.rst

@@ -61,7 +61,7 @@ Select the tab for the **Installed** mode at the bottom of the screen.
 .. figure:: images/gnome-software-installed.png
    :align: center
    :scale: 50%
-   :alt: The GNOME Software installed software screen
+   :alt: The GNOME Software installed software page
 
    The installed software page shows the applications and components that have been installed.
 
@@ -138,7 +138,7 @@ It is a good idea to update applications and other components regularly to ensur
 .. figure:: images/gnome-software-updates.png
    :align: center
    :scale: 50%
-   :alt: The GNOME Software updates screen
+   :alt: The GNOME Software updates page
 
    The updates page shows the applications and components that require updating.
 
@@ -156,8 +156,35 @@ When you update an application, the button to the right of it becomes an update
 
 The application or component will be removed from the list of updates after it has been updated.
 
+You can configure how updates are handled by opening the application menu and selecting the **Update Preferences** item.
+
+.. figure:: images/gnome-software-menu.png
+   :align: center
+   :alt: Opening the application menu
+
+   The application menu contains an option to change the update preferences.
+
+Selecting this item opens a page that allows you to configure 
+
+.. figure:: images/gnome-software-update-preferences.png
+   :align: center
+   :alt: The Update Preferences page
+
+   The Update Preferences page contains options for managing software updates.
+
+When you have adjusted the options, press the back button to return to the previous view.
+
 .. _package_management_gnome_software_sources:
 
 Adding New Software Sources
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
+Packages can be downloaded from a variety of sources. To configure these, open the menu by pressing the button at the right hand edge of the header bar.
+
+.. figure:: images/gnome-software-menu.png
+   :align: center
+   :alt: Opening the application menu
+
+   The application menu contains an option to configure the software repositories.
+
+Select the **Software Repositories** item to launch a separate tool for adding, removing and configuring the remote repositories containing software that can be downloaded.