[CONTINT-4562] Add a CHANGELOG.md entry

Author: L3n41c

CHANGELOG.md

@@ -8,6 +8,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## Added
 - Introduce a `container` generator able to generate an arbitrary number
   of docker containers
+- Compute the Working Set Size of the target thanks to the Linux Idle Page Tracking API.
+  And expose it in the new `total_wss_bytes` metric.
 ## Changed
 - Lading's byte-unit crate is now updated to 5.x. This version of the crate is
   very strict about the difference between MiB, Mb etc.