updated changelog

CHANGELOG.txt

-Changes in Release 1.2.2
+Changes In Release 1.2.3
+--------------------------------------------------------------------------------
+
+  * PDBWriter: Prevent writing of out-of-bounds atom coordinates.
 
+Changes in Release 1.2.2
+--------------------------------------------------------------------------------
   * Fixed loop indentation in the PDBize function for bio units, leading to
     exponential running time/ memory consumption. This problem only affected a
     fraction of PDB entries.