Fixing aspnet/KestrelHttpServer url (dotnet#900)

README.md

@@ -163,7 +163,7 @@ The library is used by a large number of projects for performance discussions or
 * [CoreFX](https://github.com/dotnet/corefx/issues?utf8=✓&q=BenchmarkDotNet) (.NET Core foundational libraries;
   see also [official benchmarking guide](https://github.com/dotnet/corefx/blob/master/Documentation/project-docs/benchmarking.md)),
 * [Roslyn](https://github.com/dotnet/roslyn/search?q=BenchmarkDotNet&type=Issues&utf8=✓) (C# and Visual Basic compiler)
-* [KestrelHttpServer](https://github.com/aspnet/KestrelHttpServer/tree/dev/benchmarks/Kestrel.Performance) (A cross platform web server for ASP.NET Core)
+* [KestrelHttpServer](https://github.com/aspnet/KestrelHttpServer/tree/master/benchmarks/Kestrel.Performance) (A cross platform web server for ASP.NET Core)
 * [SignalR](https://github.com/aspnet/SignalR/tree/dev/benchmarks/Microsoft.AspNetCore.SignalR.Microbenchmarks)
 * [EntityFrameworkCore](https://github.com/aspnet/EntityFrameworkCore/tree/dev/benchmarks)
 * [F#](https://github.com/fsharp/fsharp/blob/master/tests/scripts/array-perf/array-perf.fs)