DOC: Add documentation for the plot curve editor.

docs/source/widgets/curve_editor.rst

@@ -0,0 +1,26 @@
+#######################
+Plot Curve Editor
+#######################
+
+PyDM plot widgets keep the inventory of curves in the ``curves`` property which
+is a list of JSON strings containing the definition of parameters for each of
+the curves in a plot.
+
+Since editing a list of JSON strings via Qt Designer is very unfriendly and
+error prone, PyDM offers the Plot Curve Editor extension which can be invoked
+via a Right-click and selecting the "Edit Curves..." item in the context menu
+that pops-up.
+
+.. figure:: /_static/widgets/curve_editor/curve_editor.gif
+   :scale: 100 %
+   :align: center
+   :alt: Curve Editor in Action
+
+   This animation demonstrates how to use the Curve Editor that is common to
+   all the PyDM plot widgets.
+
+
+.. Note::
+  This is not applicable for users interacting with widgets via Python code.
+  In this case you will need to serialize the list of JSON strings and use the
+  ``setCurves`` property to configure the plot properly.

docs/source/widgets/index.rst

@@ -37,6 +37,7 @@ Plot Widgets
 .. toctree::
    :maxdepth: 1
 
+   curve_editor.rst
    scatterplot.rst
    timeplot.rst
    waveformplot.rst