docs: add name of new chart type to changelog entry

Signed-off-by: F.N. Claessen <felix@seita.nl>

documentation/changelog.rst

@@ -11,7 +11,7 @@ v0.15.0 | July XX, 2023
 New features
 -------------
 
-* Users can select a new chart type on the sensor page of the UI, to show how sensor values are distributed over the time of day [see `PR #715 <https://www.github.com/FlexMeasures/flexmeasures/pull/715>`_]
+* Users can select a new chart type (daily heatmap) on the sensor page of the UI, showing how sensor values are distributed over the time of day [see `PR #715 <https://www.github.com/FlexMeasures/flexmeasures/pull/715>`_]
 * Allow deleting multiple sensors with a single call to ``flexmeasures delete sensor`` by passing the ``--id`` option multiple times [see `PR #734 <https://www.github.com/FlexMeasures/flexmeasures/pull/734>`_]
 * Make it a lot easier to read off the color legend on the asset page, especially when showing many sensors, as they will now be ordered from top to bottom in the same order as they appear in the chart (as defined in the ``sensors_to_show`` attribute), rather than alphabetically [see `PR #742 <https://www.github.com/FlexMeasures/flexmeasures/pull/742>`_]
 * Having percentages within the [0, 100] domain is such a common use case that we now always include it in sensor charts with % units, making it easier to read off individual charts and also to compare across charts [see `PR #739 <https://www.github.com/FlexMeasures/flexmeasures/pull/739>`_]