Update CHANGELOG.md

CHANGELOG.md

@@ -17,6 +17,7 @@
     GitLab Runner cannot handle the load
 * Use the `OVLP_AMG_4_DG` linear solver for all computations, including
     sequential ones. This significantly improves performance for large problems.
+* Change compilation order which reduces RAM usage when compiling in parallel.
 
 ### Fixed
 * The source code is now compatible to the Clang LLVM compiler.