docs: add changelog entry

Signed-off-by: Victor Garcia Reolid <victor@seita.nl>

documentation/changelog.rst

@@ -25,7 +25,7 @@ Infrastructure / Support
 
 * Add support for profiling Flask API calls using ``pyinstrument`` (if installed). Can be enabled by setting the environment variable ``FLEXMEASURES_PROFILE_REQUESTS`` to ``True`` [see `PR #722 <https://www.github.com/FlexMeasures/flexmeasures/pull/722>`_]
 * The endpoint `[POST] /health/ready <api/v3_0.html#get--api-v3_0-health-ready>`_ returns the status of the Redis connection, if configured [see `PR #699 <https://www.github.com/FlexMeasures/flexmeasures/pull/699>`_]
-
+* Document the linear program in the `device_scheduler`function [see `PR #764 <https://www.github.com/FlexMeasures/flexmeasures/pull/764>`_].
 
 /api/v3_0/health/ready