indicate immutable actions are only available for internal use at this time

Author: KyFaSt

actions/ql/src/Security/CWE-829/UnversionedImmutableAction.md

@@ -2,11 +2,11 @@
 
 ## Description
 
-This action is eligible for immutable actions which are released as packages in the GitHub package registry instead of resolved from a pinned SHA at the repository. The immutable action provides the same immutability as pinning the version to a SHA but with improved readability.
+This action is eligible for a new GitHub feature called Immutable Actions that is currently only available for internal users but will be publicly available soon. Immutable Actions are released as packages in the GitHub package registry instead of resolved from a pinned SHA at the repository. The immutable action provides the same immutability as pinning the version to a SHA but with improved readability.
 
 ## Recommendations
 
-When using [immutable actions](https://github.com/github/package-registry-team/blob/main/docs/immutable-actions/immutable-actions-howto.md) use the full semantic version of the action. This will ensure that the action is resolved to the exact version stored in the GitHub package registry.
+For internal users: when using [immutable actions](https://github.com/github/package-registry-team/blob/main/docs/immutable-actions/immutable-actions-howto.md) use the full semantic version of the action. This will ensure that the action is resolved to the exact version stored in the GitHub package registry.
 
 ## Examples