Add reference to mastodon/chart (#22589)

Reference mastodon/chart in the deployment section

README.md

@@ -75,7 +75,7 @@ Mastodon acts as an OAuth2 provider, so 3rd party apps can use the REST and Stre
 - **Ruby** 2.7+
 - **Node.js** 16+
 
-The repository includes deployment configurations for **Docker and docker-compose** as well as specific platforms like **Heroku**, **Scalingo**, and **Nanobox**. The [**standalone** installation guide](https://docs.joinmastodon.org/admin/install/) is available in the documentation.
+The repository includes deployment configurations for **Docker and docker-compose** as well as specific platforms like **Heroku**, **Scalingo**, and **Nanobox**. For Helm charts, reference the [mastodon/chart repository](https://github.com/mastodon/chart). The [**standalone** installation guide](https://docs.joinmastodon.org/admin/install/) is available in the documentation.
 
 A **Vagrant** configuration is included for development purposes. To use it, complete following steps: