Update changelog link for 9/23 release (#59)

replaces the CMS Eco Jira card # with the GitHub PR

CHANGELOG.md

@@ -24,7 +24,7 @@
 * Move Pantheon modifications in application.php ([#29](https://github.com/pantheon-systems/wordpress-composer-managed/pull/29))
 
 ### 2022-09-23
-* `.gitignore` updates - Reported in the Pantheon Community Slack channel was the fact that the `.gitignore` included in this repository did not match the `.gitignore` (with commonly-ignored files) in the default [WordPress upstream](https://github.com/pantheon-systems/wordpress) (CMS-956)
+* `.gitignore` updates - Reported in the Pantheon Community Slack channel was the fact that the `.gitignore` included in this repository did not match the `.gitignore` (with commonly-ignored files) in the default [WordPress upstream](https://github.com/pantheon-systems/wordpress) ([#24](https://github.com/pantheon-systems/wordpress-composer-managed/pull/24))
 * Use `.env.local` for local development ([#26](https://github.com/pantheon-systems/wordpress-composer-managed/pull/26)) - Fixes an issue where Lando was not using `.env` files locally.
 * README updates ([#27](https://github.com/pantheon-systems/wordpress-composer-managed/pull/27) and [#28](https://github.com/pantheon-systems/wordpress-composer-managed/pull/28)) - Adds link to https://github.com/pantheon-upstreams/wordpress-composer-managed for forking, as well as additional guidance about the default branch name for custom upstreams.