Rename beta SDKs to public preview SDKs in readme (#3126)

* Rename beta SDKs to public preview SDKs in readme

* replace-with-the-version-of-your-choice

* Update README.md

Author: ramya-stripe

README.md

@@ -264,27 +264,21 @@ You can disable this behavior if you prefer:
 StripeConfiguration.EnableTelemetry = false;
 ```
 
-### Beta SDKs
+### Public Preview SDKs
 
-Stripe has features in the beta phase that can be accessed via the beta version of this package.
-We would love for you to try these and share feedback with us before these features reach the stable phase.
-To install a beta version of Stripe.net use the version parameter with `dotnet add package` command:
+Stripe has features in the [public preview phase](https://docs.stripe.com/release-phases) that can be accessed via versions of this package that have the `-beta.X` suffix like `45.1.0-beta.2`.
+We would love for you to try these as we incrementally release new features and improve them based on your feedback.
+
+To install, choose the version that includes support for the preview feature you are interested in by reviewing the [releases page](https://github.com/stripe/stripe-dotnet/releases/) and then use it in the version parameter with `dotnet add package` command:
 
 ```
-dotnet add package Stripe.net --version <beta version>
+dotnet add package Stripe.net --version <replace-with-the-version-of-your-choice>
 ```
 
-Beta versions are appended with `-beta.X` such as `45.0.0-beta.1`. Make sure to choose the version that includes support for the beta you are interested in!
-
 > **Note**
-> There can be breaking changes between beta versions. Therefore we recommend pinning the package version to a specific beta version in your project file. This way you can install the same version each time without breaking changes unless you are intentionally looking for the latest beta version.
-
-We highly recommend keeping an eye on when the beta feature you are interested in goes from beta to stable so that you can move from using a beta version of the SDK to the stable version.
+> There can be breaking changes between two versions of the public preview SDKs without a bump in the major version. Therefore we recommend pinning the package version to a specific version in your project file. This way you can install the same version each time without breaking changes unless you are intentionally looking for the latest public preview SDK.
 
-If your beta feature requires a `Stripe-Version` header to be sent, set the `StripeConfiguration.ApiVersion` property with the `StripeConfiguration.AddBetaVersion` function:
-
-> **Note**
-> The `ApiVersion` can only be set in beta versions of the library.
+Some preview features require a name and version to be set in the `Stripe-Version` header like `feature_beta=v3`. If your preview feature has this requirement, use the `StripeConfiguration.AddBetaVersion` function (available only in the public preview SDKs):
 
 ```csharp
 StripeConfiguration.AddBetaVersion("feature_beta", "v3");