Add saving package list to muon

source/4/4.2/muon.rst

@@ -15,6 +15,8 @@ If you want to see your history of package updates and installed from the :menus
 
 To check for updates in muon press :kbd:`Control + R` or the gear button with an arrow or :menuselection:`Edit --> Check for Updates`.  
 
+If you want to save all of your packages on a text file you can :menuselection:`File --> Save Download Pakcage List`. 
+
 Screenshot
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 .. image:: muon.png