docs: clarify private preview SDK access in README (#1875)

Committed-By-Agent: claude

Author: jar-stripe

README.md

@@ -351,7 +351,7 @@ Stripe.add_beta_version("feature_beta", "v3")
 
 ### Private Preview SDKs
 
-Stripe has features in the [private preview phase](https://docs.stripe.com/release-phases) that can be accessed via versions of this package that have the `-alpha.X` suffix like `11.2.0-alpha.2`. These are invite-only features. Once invited, you can install the private preview SDKs by following the same instructions as for the [public preview SDKs](https://github.com/stripe/stripe-ruby?tab=readme-ov-file#public-preview-sdks) above and replacing the term `beta` with `alpha`.
+Stripe has features in the [private preview phase](https://docs.stripe.com/release-phases) that can be accessed via versions of this package that have the `-alpha.X` suffix like `11.2.0-alpha.2`. You can install the private preview SDKs by following the same instructions as for the [public preview SDKs](https://github.com/stripe/stripe-ruby?tab=readme-ov-file#public-preview-sdks) above and replacing the term `beta` with `alpha`. Note that access to specific private preview API features may require separate approval.
 
 ### Custom requests