Updated CHANGELOG

(cherry picked from commit c367509c)

CHANGELOG.md

@@ -7,6 +7,8 @@ v4.3.1
 - Add `THIRDPARTY_USE_SSL` option to disable use of SSL on systems where CMake
   is not compiled with SSL support. (!602)
 - Fix Homogeneous transform when unshuffling is not used. (!599)
+- Fix bug in modified Arnoldi algorithm causing convergence to be reported when
+  number of vectors is less than `nvec` (!608)
 
 **NekMesh**:
 - Fix incorrect link directory on CCMIO library.