Update CHANGELOG for 8x (#2645)

CHANGELOG.md

@@ -1,10 +1,24 @@
 See the [releases](https://github.com/AzureAD/azure-activedirectory-identitymodel-extensions-for-dotnet/releases) for details on bug fixes and added features.
 
-
-Pending Next Release
+8.0.0-preview1
+====
+### Breaking changes:
+- IdentityModel 8x no longer supports .net461, which has reached end of life and is no longer supported. See issue [#2544](https://github.com/AzureAD/azure-activedirectory-identitymodel-extensions-for-dotnet/issues/2544) for details.
+- Two IdentityModel extension dlls `Microsoft.IdentityModel.KeyVaultExtensions` and `Microsoft.IdentityModel.ManagedKeyVaultSecurityKey` were using ADAL, which is no longer supported . The affected packages have been removed, as the replacement is to use [Microsoft.Identity.Web](https://github.com/AzureAD/microsoft-identity-web/wiki/Certificates). See issue [#2454](https://github.com/AzureAD/azure-activedirectory-identitymodel-extensions-for-dotnet/issues/2454) for details.
+- `AppContext.SetSwitch` which were included in IdentityModel 7x, have been removed and are the default in IdentityModel 8x. The result is a more performant IdentityModel by default. See issue [#2629](https://github.com/AzureAD/azure-activedirectory-identitymodel-extensions-for-dotnet/issues/2629) for details.
+
+7.6.1
 =====
+### New Features:
+- Add  missing metadata parameters to OpenIdConnectConfiguration. See issue [#2498](https://github.com/AzureAD/azure-activedirectory-identitymodel-extensions-for-dotnet/issues/2498) for details. 
+
 ### Bug Fixes:
+- Fix over-reporting of `IDX14100`. See issue [#2058](https://github.com/AzureAD/azure-activedirectory-identitymodel-extensions-for-dotnet/issues/2058) and PR [#2618](https://github.com/AzureAD/azure-activedirectory-identitymodel-extensions-for-dotnet/pull/2618) for details.
+- `JwtRegisteredClaimNames` now contains previously missing Standard OpenIdConnect claims. See issue [#1598](https://github.com/AzureAD/azure-activedirectory-identitymodel-extensions-for-dotnet/issues/1598) for details.
+
+### Performance Improvements:
 - Reduced allocations in `AadIssuerValidator` by not using `string.Replace` where appropriate. See issue [#2595](https://github.com/AzureAD/azure-activedirectory-identitymodel-extensions-for-dotnet/issues/2595) and PR [#2597](https://github.com/AzureAD/azure-activedirectory-identitymodel-extensions-for-dotnet/pull/2597) for more details.
+- No longer for every string claim, calling DateTime.TryParse on each value, whether it is expected to be a DateTime or not. See issue [#2615](https://github.com/AzureAD/azure-activedirectory-identitymodel-extensions-for-dotnet/issues/2615) for details.
 
 7.6.0
 =====