(DOCSP-9962): Add tooltip detail for scatter charts (#355)

Author: jeff-allen-mongo

source/chart-type-reference/geospatial-scatter.txt

@@ -84,6 +84,21 @@ sizes.
    If no fields are encoded in the :guilabel:`Size` encoding channel,
    |charts-short| displays all points with the same size.
 
+Tooltip Detail
+~~~~~~~~~~~~~~
+
+*(Optional)* The :guilabel:`Tooltip Detail` encoding channel adds
+the value of the selected field to each data point's tooltip. To
+view a data point tooltip, hover over that point in the chart.
+
+In addition to the :guilabel:`Tooltip Detail` field, the tooltip also
+shows other fields used to construct the chart.
+
+For example, the following chart encodes the :guilabel:`Summary`
+field as a :guilabel:`Tooltip Detail`:
+
+.. figure:: /images/charts/geospatial-scatter-tooltip-example.png
+
 
 Build a Geospatial Scatter Chart
 --------------------------------

source/chart-type-reference/scatter-chart.txt

@@ -41,15 +41,23 @@ Scatter charts provide the following :ref:`encoding channels
 
    * - Color
      - *(Optional)* A :guilabel:`category` encoding channel that changes
-       the color of the data point markers to indicate a corresponding
-       data value. |charts| lists the colors used in a key to the right of
-       the chart.
+       the color of the data point markers based on the value of the
+       selected field. |charts| lists the colors used in a key to the
+       right of the chart.
 
    * - Shape
      - *(Optional)* A :guilabel:`category` encoding channel that changes
-       the shape of the data point markers to indicate a corresponding
-       data value. |charts| lists the shapes used in a key to the right of
-       the chart.
+       the shape of the data point markers based on the value of the
+       selected field. |charts| lists the shapes used in a key to the
+       right of the chart.
+
+   * - Tooltip Detail
+     - *(Optional)* A :guilabel:`category` encoding channel that adds
+       the value of the selected field to each data point's tooltip. To
+       view a data point tooltip, hover over that point in the chart.
+
+       In addition to the :guilabel:`Tooltip Detail` field, the tooltip
+       also shows other fields used to construct the chart.
 
 Use Cases
 ---------