Update CHANGELOG.md

Author: gecko0307

CHANGELOG.md

@@ -2,6 +2,8 @@ dlib 1.7.0 - TBD
 ----------------
 - **dlib.math**
   - New module `dlib.math.base`, a direct replacement for `std.math` that implicitly uses LLVM intrinsics instead of Phobos functions when possible for maximum performance
+  - SIMD-optimized 4x4 matrix multiplication
+  - `dlib.math.sse` was removed. This module is unmaintained, broken on x86_64, and effectively obsolete now because `dlib.math.matrix` directly includes SIMD optimizations, and vector operations don't actually need them
 - **dlib.container**
   - New module `dlib.container.hashmap`, a flat hash map implementation that is faster than both `dlib.container.dict` and native associative arrays
 - **dlib.hash**