Update documentation

Author: paulbalandan

user_guide_src/source/changelogs/v4.2.0.rst

@@ -29,6 +29,7 @@ Enhancements
 - Added new OCI8 driver for database.
     - It can access Oracle Database and supports SQL and PL/SQL statements.
 - The ``spark routes`` command now shows closure routes, auto routtes, and filters. See :ref:`URI Routing <spark-routes>`.
+- BaseConfig's ability to convert ``.env`` values has improved. Numeric strings will be converted to either integers or floats. String "null" will be changed to ``null``. String "empty" will be changed to ``''``.
 
 Changes
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