Clarify introduction of new authentication method.

Author: MarkvanMents

content/en/docs/appstore/use-content/platform-supported-content/modules/oidc.md

@@ -321,7 +321,7 @@ In this case, the OIDC client is the app you are making.
     The options are:
     * `client_secret_basic`: Your app will use the HTTP Basic Authentication scheme to authenticate itself at your IdP. This is the default. The `client_secret_basic` makes use of the `client-id` and `client-secret`.
     * `client_secret_post`: Your app will authenticate itself by including its `client_id` and `client_secret` in the payload of token requests. (Older versions of the OIDC SSO module used this method.)
-    * `private_key_jwt`: This method uses asymmetric key cryptography (algorithm) for authentication. This is the best option for security. When you select the `private key` option, you can configure the following fields:
+    * `private_key_jwt`: This method, introduced in version 4.1.0, uses asymmetric key cryptography (algorithm) for authentication. This is the best option for security. When you select the `private key` option, you can configure the following fields:
         * **Key Pair Expiration Days**: (default `90`)
         * **JWT ALG(Signing Algorithm)**: (default `RS256`)