Update CHANGELOG.md for 1.15.8 (#26662)

CHANGELOG.md

@@ -2,6 +2,29 @@
 - [v1.0.0 - v1.9.10](CHANGELOG-pre-v1.10.md)
 - [v0.11.6 and earlier](CHANGELOG-v0.md)
 
+## 1.15.8 Enterprise
+### April 24, 2024
+
+CHANGES:
+
+* core: Bump Go version to 1.21.9.
+* ui: Update dependencies including D3 libraries [[GH-26346](https://github.com/hashicorp/vault/pull/26346)]
+
+IMPROVEMENTS:
+
+* activity (enterprise): Change minimum retention window in activity log to 48 months
+* core: make the best effort timeout for encryption count tracking persistence configurable via an environment variable. [[GH-25636](https://github.com/hashicorp/vault/pull/25636)]
+* license utilization reporting (enterprise): Add retention months to license utilization reports.
+* sdk/decompression: DecompressWithCanary will now chunk the decompression in memory to prevent loading it all at once. [[GH-26464](https://github.com/hashicorp/vault/pull/26464)]
+* ui: show banner instead of permission denied error when batch token is expired [[GH-26396](https://github.com/hashicorp/vault/pull/26396)]
+
+BUG FIXES:
+
+* core (enterprise): fix bug where raft followers disagree with the seal type after returning to one seal from two. [[GH-26523](https://github.com/hashicorp/vault/pull/26523)]
+* secrets/pki: fixed validation bug which rejected ldap schemed URLs in crl_distribution_points. [[GH-26477](https://github.com/hashicorp/vault/pull/26477)]
+* storage/raft (enterprise): Fix a bug where autopilot automated upgrades could fail due to using the wrong upgrade version
+* ui: fixed a bug where the replication pages did not update display when navigating between DR and performance [[GH-26325](https://github.com/hashicorp/vault/pull/26325)]
+
 ## 1.15.7 Enterprise
 ### March 28, 2024