Backport PR #341: changelog for 5.2.2

Author: takluyver

docs/changelog.rst

@@ -4,12 +4,28 @@
 Changes in Jupyter Client
 =========================
 
+5.2.2
+=====
+
+`5.2.2 on GitHub <https://github.com/jupyter/jupyter_client/milestones/5.2.2>`__
+
+- Fix :meth:`.KernelSpecManager.get_all_specs` method in subclasses
+  that only override :meth:`.KernelSpecManager.find_kernel_specs`
+  and :meth:`.KernelSpecManager.get_kernel_spec`.
+  See :ghissue:`338` and :ghpull:`339`.
+- Eliminate occasional error messages during process exit (:ghpull:`336`).
+- Improve error message when attempting to bind on invalid address (:ghpull:`330`).
+- Add missing direct dependency on tornado (:ghpull:`323`).
+
+
 5.2.1
 =====
 
+`5.2.1 on GitHub <https://github.com/jupyter/jupyter_client/milestones/5.2.1>`__
+
 - Add parenthesis to conditional pytest requirement to work around a bug in the
   ``wheel`` package, that generate a ``.whl`` which otherwise always depends on
-  ``pytest`` see :ghissue:`324` and :ghpull:`325`
+  ``pytest`` see :ghissue:`324` and :ghpull:`325`.
 
 5.2
 ===