base: Add changelog entry for CLC #188

This proposal modified the implementations of copyBytes, moveBytes and
fillBytes (as detailed in the proposal)

https://github.com/haskell/core-libraries-committee/issues/188

libraries/base/changelog.md

@@ -41,6 +41,7 @@
   * Make `Semigroup`'s `stimes` specializable. ([CLC proposal #8](https://github.com/haskell/core-libraries-committee/issues/8))
   * Deprecate `Data.List.NonEmpty.unzip` ([CLC proposal #86](https://github.com/haskell/core-libraries-committee/issues/86))
   * Fixed exponent overflow/underflow bugs in the `Read` instances for `Float` and `Double` ([CLC proposal #192](https://github.com/haskell/core-libraries-committee/issues/192))
+  * Implement `copyBytes`, `fillBytes`, `moveBytes` and `stimes` for `Data.Array.Byte.ByteArray` using primops ([CLC proposal #188](https://github.com/haskell/core-libraries-committee/issues/188))
 
 ## 4.18.0.0 *March 2023*
   * Shipped with GHC 9.6.1