Update changelog for release

docs/CHANGELOG.rst

@@ -4,6 +4,25 @@ pontibus Change Log
 
 .. current developments
 
+vv0.5.0
+====================
+
+**Changed:**
+
+* In line with Interchange v0.5+, the box is no longer being scaled by 1.1
+  when defining the ``number_of_solvent_molecules``. In those cases, the
+  resulting box density will be much higher.
+  If you were defining ``number_of_solvent_molecules`` and then you will
+  need to scale the density by `(1 / (1.1^3)` instead of using the
+  default `target_density` (currently default of 0.95 * unit.grams / unit.mL).
+  In practice this means setting `target_density` to roughly
+  0.715 unit.grams / unit.mL when setting `number_of_solvent_molecules`.
+* The ASFE and HybridTop Protocols have been updated to work
+  with openfe v1.9. Notably this means that the Protocols have
+  now been split into three ProtocolUnits (PR #190).
+
+
+
 v0.4.0
 ====================