Update features with new save methods

Author: kpinnipa

docs/user/features.rst

@@ -4,8 +4,10 @@ Features
 Creation of a New Snippet
 -------------------------
 
--  Right click and save highlighted code (lines of code)
--  Drag cell into panel to save (lines of code)
+-  Right click and save highlighted lines of code
+-  Drag cell into panel to save
+-  Select cell(s) and right click to save content as snippet
+-  Select cell(s) and use keyboard shortcut (cmd-shift-A or ctrl-shift-A) to save content as snippet
 .. image:: ../../Design/add_snippet.png
 
 -  Plus button to create a new snippet from scratch