Add multithreaded ASan and LSan to changelog [ci skip] (emscripten-core#9229)

Author: quantum5

ChangeLog.md

@@ -18,6 +18,9 @@ See docs/process.md for how version tagging works.
 
 Current Trunk
 -------------
+ - Add support for [address sanitizer](https://clang.llvm.org/docs/AddressSanitizer.html)
+   and standalone [leak sanitizer](https://clang.llvm.org/docs/LeakSanitizer.html)
+   with multiple threads. (#9060, #9076)
  - Remove ERROR_ON_MISSING_LIBRARIES setting (it's always on now)
  - Remove the ability to use Python operators in flags that support KB/MB/GB/TB
    suffixes, e.g. `TOTAL_MEMORY`. This means that `-s TOTAL_MEMORY=1024*1024`