Added duplicate action button documentation

docs/user_manual/working_with_vector/vector_properties.rst

@@ -2967,6 +2967,24 @@ The second example uses the \%\% notation, which does not rely on a particular
 field for its value. When the action is invoked, the \%\% will be replaced by
 the value of the selected field in the identify results or attribute table.
 
+.. index:: Actions, Attribute Actions
+   single: Actions; Duplicate an action
+.. _duplicating_actions:
+
+Duplicating Actions
+-------------------
+
+QGIS allows you to duplicate existing actions. To duplicate an attribute action, 
+open the vector :guilabel:`Layer Properties` dialog and click on the :guilabel:`Actions` tab. 
+In the :guilabel:`Actions` tab, click the |duplicateAction| :sup:`Duplicate an action`
+to open the :guilabel:`Duplicate Action` dialog. You must have selected at least one existing action 
+in order to create a duplicate.
+
+In the dialogue that appears, make any changes that are necessary. See :ref:`adding_actions` 
+for further information. Once finished, press :guilabel:`OK` to create a duplicate of the action with 
+any changes that you made. If you did not edit the description, or if you changed it to be 
+identical to the description of any other existing action, "_1" will be added to the end of it.
+
 .. index::
    single: Actions; Using actions
 .. _using_actions:
@@ -3758,6 +3776,8 @@ To do so:
    :width: 1.5em
 .. |display| image:: /static/common/display.png
    :width: 1.5em
+.. |duplicateAction| image:: /static/common/mActionDuplicateLayout.png
+   :width: 1.5em
 .. |editMetadata| image:: /static/common/editmetadata.png
    :width: 1.2em
 .. |elevationscale| image:: /static/common/elevationscale.png