Update README.md to clarify the support policy

README.md

@@ -32,7 +32,7 @@ can be found in the [dedicated repository](https://github.com/openiddict/openidd
 
 ## Compatibility matrix
 
-| Web framework version | .NET runtime version | OpenIddict 4.x                          | OpenIddict 5.x (preview)                |
+| Web framework version | .NET runtime version | OpenIddict 4.x                          | OpenIddict 5.x                          |
 |-----------------------|----------------------|-----------------------------------------|-----------------------------------------|
 | ASP.NET Core 2.1      | .NET Framework 4.6.1 | :heavy_check_mark: :information_source: | :heavy_check_mark: :information_source: |
 | ASP.NET Core 2.1      | .NET Framework 4.7.2 | :heavy_check_mark:                      | :heavy_check_mark:                      |
@@ -121,9 +121,22 @@ You should receive a response within 24 hours. If for some reason you do not, pl
 If you need support, please make sure you [sponsor the project](https://github.com/sponsors/kevinchalet) before creating a GitHub ticket.
 If you're not a sponsor, you can post your questions on Gitter or StackOverflow:
 
-- **Gitter: [https://gitter.im/openiddict/openiddict-core](https://gitter.im/openiddict/openiddict-core)**
+- **Gitter: [https://app.gitter.im/#/room/#openiddict_openiddict-core:gitter.im](https://app.gitter.im/#/room/#openiddict_openiddict-core:gitter.im)**
 - **StackOverflow: [https://stackoverflow.com/questions/tagged/openiddict](https://stackoverflow.com/questions/tagged/openiddict)**
 
+> **Note**
+> With OpenIddict 5.0 being now generally available, the previous version, OpenIddict 4.0, stops being supported and won't receive bug
+> fixes or security updates. As such, it is recommended to migrate to OpenIddict 5.0 to continue receiving bug and security fixes.
+> 
+> **There are, however, two exceptions to this policy**:
+>   - **ABP Framework 7.0 users will still receive patches for OpenIddict 4.x for as long as ABP Framework 7.0 itself is supported by Volosoft**
+>   (typically a year following the release of ABP 8.0), whether they have a commercial ABP license or just use the free packages.
+> 
+>   - **OpenIddict sponsors who have opted for a $250+/month sponsorship are now offered extended support:**
+>     - $250/month sponsors get full support for OpenIddict 4.x until June 18, 2024 (6 months).
+>     - $500/month sponsors get full support for OpenIddict 4.x until December 18, 2024 (12 months).
+>     - $1,000/month sponsors get full support for OpenIddict 4.x until December 18, 2025 (24 months).
+
 --------------
 
 ## Nightly builds