Add changelog entry for MATH-1155.

src/changes/changes.xml

@@ -54,6 +54,12 @@ If the output is not quite correct, check for invisible trailing spaces!
     </release>
 
     <release version="4.0" date="XXXX-XX-XX" description="">
+      <action dev="tn" type="update" issue="MATH-1155">
+        WELL type pseudo-random number generators have been refactored:
+        the cached indirection index tables per instance are now stored
+        in a static instance. This reduces the initialization cost when
+        creating a new instance.
+      </action>
       <action dev="evanward" type="fix" issue="MATH-1204">
         "UnivariateSolverUtils#bracket(...)" sometimes failed to bracket
         if a reached the lower bound.