Changelog and readme.txt edits. (#45901)

Committed via a GitHub action: https://github.com/Automattic/jetpack/actions/runs/19305942652

Upstream-Ref: Automattic/jetpack@130e3f4

Author: tbradsha

composer.json

@@ -9,7 +9,7 @@
 	},
 	"require-dev": {
 		"yoast/phpunit-polyfills": "^4.0.0",
-		"automattic/jetpack-changelogger": "^6.0.9-alpha",
+		"automattic/jetpack-changelogger": "^6.0.9",
 		"automattic/phpunit-select-config": "^1.0.3"
 	},
 	"suggest": {