Fixes broken link to install github + slack app (#58460)

Author: jules-p

content/copilot/how-tos/use-copilot-agents/coding-agent/integrate-coding-agent-with-slack.md

@@ -42,7 +42,7 @@ You can send the {% data variables.product.prodname_github_app %} direct message
 
 You must have write access to the default repository – or the repository specified in your prompt – in order to trigger {% data variables.copilot.copilot_coding_agent %} to work. If you do not have write access to the relevant repository, you can still help guide {% data variables.product.prodname_copilot_short %} by providing input in the Slack thread, which will be used as context when {% data variables.copilot.copilot_coding_agent %} makes changes in the pull request.
 
-Users can invoke {% data variables.copilot.copilot_coding_agent %} on any repository where they have `write` access. For enterprise-owned repositories, administrators must install and configure the [Slack {% data variables.product.prodname_github_app %}](https://github.com/organizations/github/settings/apps/slack?ref_product=copilot&ref_type=engagement&ref_style=text&ref_plan=enterprise&utm_source=docs-web-settings-apps-slack-copilot&utm_medium=docs&utm_campaign=universe25post) and specify which repositories the Slack app can access. For more information about configuring {% data variables.product.prodname_github_apps %}, see [AUTOTITLE](/apps/using-github-apps/installing-a-github-app-from-github-marketplace-for-your-organizations).
+Users can invoke {% data variables.copilot.copilot_coding_agent %} on any repository where they have `write` access. For enterprise-owned repositories, administrators must install and configure the [Slack {% data variables.product.prodname_github_app %}](https://github.com/marketplace/slack-github?ref_product=copilot&ref_type=engagement&ref_style=text&ref_plan=enterprise&utm_source=docs-web-settings-apps-slack-copilot&utm_medium=docs&utm_campaign=universe25post) and specify which repositories the Slack app can access. For more information about configuring {% data variables.product.prodname_github_apps %}, see [AUTOTITLE](/apps/using-github-apps/installing-a-github-app-from-github-marketplace-for-your-organizations).
 
 1. In Slack, open a direct message with the {% data variables.product.prodname_github_app %} or mention the app in a thread by typing `@{% data variables.product.prodname_copilot %}`.
 1. Type your prompt, then send it. Optionally, you can specify a repository or branch using the following syntax: