DOCSP-38612: MongoDB v3.6 deprecation (#540)

Author: norareidy

source/whats-new.txt

@@ -19,6 +19,7 @@ What's New
 
 Learn what's new in:
 
+* :ref:`Version 5.1 <version-5.1>`
 * :ref:`Version 5.0 <version-5.0>`
 * :ref:`Version 4.11 <version-4.11>`
 * :ref:`Version 4.10 <version-4.10>`
@@ -35,6 +36,26 @@ Learn what's new in:
 * :ref:`Version 4.1 <version-4.1>`
 * :ref:`Version 4.0 <version-4.0>`
 
+.. _version-5.1:
+
+What's New in 5.1
+-----------------
+
+.. warning:: Deprecations in this release
+
+   To avoid breaking changes in future major releases of the driver,
+   replace any application code that depends on deprecated program elements.
+
+.. _java-deprecations-5.1:
+
+Deprecations in 5.1
+~~~~~~~~~~~~~~~~~~~
+
+- Support for {+mdb-server+} v3.6 is deprecated and will be removed in the
+  next driver version release. To learn how to upgrade your {+mdb-server+}
+  deployment, see :manual:`Release Notes </release-notes>` in the {+mdb-server+}
+  manual.
+
 .. _version-5.0:
 
 What's New in 5.0