Update CHANGELOG

Author: Pavel Marek

CHANGELOG.md

@@ -1,5 +1,7 @@
 # 22.2.0
 * `--R.DebugLLVMLibs` is no longer a stable option.
+* Implemented `SET_GROWABLE_BIT` and `IS_GROWABLE` C API functions.
+  * This fixes installation of the `cpp11` 0.2.6 package.
 
 # 22.1.0
 * Improved performance of the `order` and `rank` builtin functions