Remove the DIM feature spec (#49424)

We merged dotnet/csharpstandard#681 at the October meeting.

Author: BillWagner

docfx.json

@@ -79,6 +79,7 @@
                     "csharp-8.0/async-streams.md",
                     "csharp-8.0/ranges.md",
                     "csharp-8.0/using.md",
+                    "csharp-8.0/default-interface-methods.md",
                     "csharp-9.0/nullable-reference-types-specification.md",
                     "csharp-9.0/nullable-constructor-analysis.md",
                     "csharp-9.0/nullable-parameter-default-value-analysis.md",
@@ -639,7 +640,6 @@
                 "_csharpstandard/standard/documentation-comments.md": "Documentation comments",
                 "_csharpstandard/standard/Bibliography.md": "Bibliography",
                 "_csharplang/proposals/csharp-8.0/patterns.md": "Recursive pattern matching",
-                "_csharplang/proposals/csharp-8.0/default-interface-methods.md": "Default interface methods",
                 "_csharplang/proposals/csharp-9.0/covariant-returns.md": "Covariant return types",
                 "_csharplang/proposals/csharp-9.0/extending-partial-methods.md": "Extending partial methods",
                 "_csharplang/proposals/csharp-9.0/extension-getenumerator.md": "Extension GetEnumerator support in foreach",
@@ -767,7 +767,6 @@
                 "_csharpstandard/standard/documentation-comments.md": "This appendix describes XML comments that are used to document your program.",
                 "_csharpstandard/standard/Bibliography.md": "This appendix lists external standards referenced in this specification.",
                 "_csharplang/proposals/csharp-8.0/patterns.md": "This feature specification describes recursive pattern matching, where patterns can nest inside other patterns.",
-                "_csharplang/proposals/csharp-8.0/default-interface-methods.md": "This feature specification describe the syntax updates necessary to support default interface methods. This includes declaring bodies in interface declarations, and supporting modifiers on declarations.",
                 "_csharplang/proposals/csharp-9.0/covariant-returns.md": "This feature specification describes covariant return types, where overriding member declarations can return a type derived from the overridden member declaration.",
                 "_csharplang/proposals/csharp-9.0/extending-partial-methods.md": "This feature specification describes extensions to partial methods. These extensions enable source generators to create or call partial methods.",
                 "_csharplang/proposals/csharp-9.0/extension-getenumerator.md": "This feature specification describes the necessary pattern for an extension method to provide the GetEnumerator support in a foreach loop.",

docs/csharp/specification/toc.yml

@@ -233,8 +233,6 @@ items:
       href: ../../../_csharplang/proposals/csharp-12.0/inline-arrays.md
   - name: Interfaces
     items:
-    - name: Default interface methods
-      href: ../../../_csharplang/proposals/csharp-8.0/default-interface-methods.md
     - name: Variance safety for static interface members
       href: ../../../_csharplang/proposals/csharp-9.0/variance-safety-for-static-interface-members.md
     - name: Static abstracts in interfaces