Fix markdown links

Author: AArnott

README.md

@@ -9,14 +9,14 @@
 
 Async synchronization primitives, async collections, TPL and dataflow extensions. The JoinableTaskFactory allows synchronously blocking the UI thread for async work. This package is applicable to any .NET application (not just Visual Studio).
 
-[Getting started](https://microsoft.github.io/vs-threading/docs/getting-started.md).
+[Getting started](https://microsoft.github.io/vs-threading/docs/getting-started.html).
 
-[See the full list of features](https://microsoft.github.io/vs-threading/docs/features.md).
+[See the full list of features](https://microsoft.github.io/vs-threading/docs/features.html).
 
 ## Microsoft.VisualStudio.Threading.Analyzers
 
 [![NuGet package](https://img.shields.io/nuget/v/Microsoft.VisualStudio.Threading.Analyzers.svg)](https://www.nuget.org/packages/Microsoft.VisualStudio.Threading.Analyzers)
 
 Static code analyzer to detect common mistakes or potential issues regarding threading and async coding.
 
-[Diagnostic analyzer rules](https://microsoft.github.io/vs-threading/analyzers/index.md).
+[Diagnostic analyzer rules](https://microsoft.github.io/vs-threading/analyzers/index.html).

doc/editorconfigs/README.md

@@ -25,7 +25,7 @@ While several project types have specific .editorconfig files defined in this fo
 Libraries that may run in any process, whether they have a main thread or not, should code themselves defensively to avoid any dependency on the main thread so that applications that do not follow `JoinableTaskFactory` rules can avoid deadlocks even when synchronously blocking their main thread using `Task.Wait()` on code running inside your library.
 In particular, shared libraries of general interest should _always_ use `.ConfigureAwait(false)` when awaiting on tasks.
 
-[Learn more about authoring libraries following best threading practices](https://microsoft.github.io/vs-threading/docs/library_with_jtf.md).
+[Learn more about authoring libraries following best threading practices](https://microsoft.github.io/vs-threading/docs/library_with_jtf.html).
 
 ### Libraries that run inside a JoinableTaskFactory-compliant application