Obsolete APIs with custom diagnostics breaking change (#21169)

Author: gewarren

docs/core/compatibility/3.1-5.0.md

@@ -210,6 +210,7 @@ If you're migrating from version 3.1 of .NET Core, ASP.NET Core, or EF Core to v
 
 ## Core .NET libraries
 
+- [API obsoletions with non-default diagnostic IDs](#api-obsoletions-with-non-default-diagnostic-ids)
 - [FrameworkDescription's value is .NET instead of .NET Core](#frameworkdescriptions-value-is-net-instead-of-net-core)
 - [Assembly-related API behavior changes for single-file publishing format](#assembly-related-api-behavior-changes-for-single-file-publishing-format)
 - [Order of tags in Activity.Tags is reversed](#order-of-tags-in-activitytags-is-reversed)
@@ -232,6 +233,10 @@ If you're migrating from version 3.1 of .NET Core, ASP.NET Core, or EF Core to v
 - [CounterSet.CreateCounterSetInstance now throws InvalidOperationException if instance already exist](#countersetcreatecountersetinstance-now-throws-invalidoperationexception-if-instance-already-exists)
 - [Microsoft.DotNet.PlatformAbstractions package removed](#microsoftdotnetplatformabstractions-package-removed)
 
+[!INCLUDE [obsolete-apis-with-custom-diagnostics](../../../includes/core-changes/corefx/5.0/obsolete-apis-with-custom-diagnostics.md)]
+
+***
+
 [!INCLUDE [frameworkdescription-returns-net-not-net-core](../../../includes/core-changes/corefx/5.0/frameworkdescription-returns-net-not-net-core.md)]
 
 ***

docs/core/compatibility/corefx.md

@@ -11,6 +11,7 @@ The following breaking changes are documented on this page:
 
 | Breaking change | Version introduced |
 | - | :-: |
+| [API obsoletions with non-default diagnostic IDs](#api-obsoletions-with-non-default-diagnostic-ids) | 5.0 |
 | [FrameworkDescription's value is .NET instead of .NET Core](#frameworkdescriptions-value-is-net-instead-of-net-core) | 5.0 |
 | [Assembly-related API behavior changes for single-file publishing format](#assembly-related-api-behavior-changes-for-single-file-publishing-format) | 5.0 |
 | [Order of tags in Activity.Tags is reversed](#order-of-tags-in-activitytags-is-reversed) | 5.0 |
@@ -53,6 +54,10 @@ The following breaking changes are documented on this page:
 
 ## .NET 5.0
 
+[!INCLUDE [obsolete-apis-with-custom-diagnostics](../../../includes/core-changes/corefx/5.0/obsolete-apis-with-custom-diagnostics.md)]
+
+***
+
 [!INCLUDE [frameworkdescription-returns-net-not-net-core](../../../includes/core-changes/corefx/5.0/frameworkdescription-returns-net-not-net-core.md)]
 
 ***