Mark recently completed C# 7.1 features as such (#19483)

docs/Language Feature Status.md

@@ -10,11 +10,11 @@ efforts behind them.
 
 | Feature | Branch | State | Developers | Reviewer | LDM Champ |
 | ------- | ------ | ----- | ---------- | -------- | --------- |
-| [Async Main](https://github.com/dotnet/csharplang/blob/master/proposals/async-main.md) | [async-main](https://github.com/dotnet/roslyn/tree/features/async-main)  | Prototype | [tyoverby](https://github.com/tyoverby) | [vsadov](https://github.com/vsadov) | [stephentoub](https://github.com/stephentoub) |
+| [Async Main](https://github.com/dotnet/csharplang/blob/master/proposals/async-main.md) | master | Merged | [tyoverby](https://github.com/tyoverby) | [vsadov](https://github.com/vsadov) | [stephentoub](https://github.com/stephentoub) |
 | [Default Expressions](https://github.com/dotnet/csharplang/blob/master/proposals/target-typed-default.md) | master  | Merged | [jcouv](https://github.com/jcouv) | [cston](https://github.com/cston) | [jcouv](https://github.com/jcouv) |
-| [Ref Assemblies](https://github.com/dotnet/roslyn/blob/features/refout/docs/features/refout.md) | [refout](https://github.com/dotnet/roslyn/tree/features/refout)  | Integration & validation | [jcouv](https://github.com/jcouv) | [gafter](https://github.com/gafter) | N/A |
-| [Infer tuple names](https://github.com/dotnet/csharplang/blob/master/proposals/csharp-7.1/infer-tuple-names.md) | master  | Merged | [jcouv](https://github.com/jcouv) | [gafter](https://github.com/gafter) | [jcouv](https://github.com/jcouv) |
-| [Pattern-matching with generics](https://github.com/dotnet/csharplang/blob/master/proposals/generics-pattern-match.md) | https://github.com/dotnet/roslyn/pull/18784  | Implementation | [gafter](https://github.com/gafter) | [agocke](https://github.com/agocke) | [gafter](https://github.com/gafter) |
+| [Ref Assemblies](https://github.com/dotnet/roslyn/blob/master/docs/features/refout.md) | master | Merged (MSBuild integration ongoing) | [jcouv](https://github.com/jcouv) | [gafter](https://github.com/gafter) | N/A |
+| [Infer tuple names](https://github.com/dotnet/csharplang/blob/master/proposals/csharp-7.1/infer-tuple-names.md) | master | Merged | [jcouv](https://github.com/jcouv) | [gafter](https://github.com/gafter) | [jcouv](https://github.com/jcouv) |
+| [Pattern-matching with generics](https://github.com/dotnet/csharplang/blob/master/proposals/generics-pattern-match.md) | master  | Merged | [gafter](https://github.com/gafter) | [agocke](https://github.com/agocke) | [gafter](https://github.com/gafter) |
 
 # C# 7.2