github_actions_ci: Update CHANGELOG and RELEASE-NOTES for shield-1.15.3

Author: draios-jenkins

charts/shield/CHANGELOG.md

@@ -10,6 +10,9 @@ Manual edits are supported only below '## Change Log' and should be used
 exclusively to fix incorrect entries and not to add new ones.
 
 ## Change Log
+# v1.15.3
+### Documentation
+* **agent** [1f478085](https://github.com/sysdiglabs/charts/commit/1f47808574f81c12f656a762c23464f458e1e524): Add App Checks example as comments ([#2340](https://github.com/sysdiglabs/charts/issues/2340))
 # v1.15.2
 ### New Features
 * **agent,shield** [62c6f923](https://github.com/sysdiglabs/charts/commit/62c6f923ba84c97589b9ea85686ccf41a4043940): release agent 14.1.1 ([#2337](https://github.com/sysdiglabs/charts/issues/2337))

charts/shield/RELEASE-NOTES.md

@@ -1,5 +1,5 @@
 # What's Changed
 
-### New Features
-- **agent,shield** [62c6f923](https://github.com/sysdiglabs/charts/commit/62c6f923ba84c97589b9ea85686ccf41a4043940): release agent 14.1.1 ([#2337](https://github.com/sysdiglabs/charts/issues/2337))
-#### Full diff: https://github.com/sysdiglabs/charts/compare/shield-1.15.1...shield-1.15.2
+### Documentation
+- **agent** [1f478085](https://github.com/sysdiglabs/charts/commit/1f47808574f81c12f656a762c23464f458e1e524): Add App Checks example as comments ([#2340](https://github.com/sysdiglabs/charts/issues/2340))
+#### Full diff: https://github.com/sysdiglabs/charts/compare/shield-1.15.2...shield-1.15.3