Remove ranges and indices

Fast follow to merging dotnet/csharpstandard#1369

Author: BillWagner

docfx.json

@@ -77,6 +77,7 @@
                     "csharp-8.0/readonly-instance-members.md",
                     "csharp-8.0/null-coalescing-assignment.md",
                     "csharp-8.0/async-streams.md",
+                    "csharp-8.0/ranges.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",
@@ -635,7 +636,6 @@
                 "_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-8.0/ranges.md": "Ranges and indices",
                 "_csharplang/proposals/csharp-8.0/using.md": "Pattern based using and using declarations",
                 "_csharplang/proposals/csharp-9.0/covariant-returns.md": "Covariant return types",
                 "_csharplang/proposals/csharp-9.0/extending-partial-methods.md": "Extending partial methods",
@@ -763,7 +763,6 @@
                 "_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-8.0/ranges.md": "This feature specification describes the syntax for ranges and indices, which support indexing individual elements of a sequence or a range of a sequence from the start or end of that sequence.",
                 "_csharplang/proposals/csharp-8.0/using.md": "This feature specification supports pattern based using and using declarations to simplify resource cleanup.",
                 "_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.",

docs/csharp/specification/toc.yml

@@ -137,8 +137,6 @@ items:
       href: ../../../_csharplang/proposals/csharp-11.0/list-patterns.md
   - name: Expressions
     items:
-    - name: Ranges
-      href: ../../../_csharplang/proposals/csharp-8.0/ranges.md
     - name: Target-typed new expressions
       href: ../../../_csharplang/proposals/csharp-9.0/target-typed-new.md
     - name: Target-typed conditional expression