Document tip about finding a JTF instance

Closes #627

doc/analyzers/VSTHRD001.md

@@ -27,6 +27,10 @@ void Foo() {
 }
 ```
 
+In the above example, we obtain a `JoinableTaskFactory` instance from the `ThreadHelper.JoinableTaskFactory` static property
+as it exists within Visual Studio itself. Other applications should create and expose their own `JoinableTaskContext` and/or `JoinableTaskFactory` for use in code that run in these applications. 
+See our doc on [consuming `JoinableTaskFactory` from a library](https://github.com/microsoft/vs-threading/blob/master/doc/library_with_jtf.md) for more information.
+
 ## Configuration
 
 This analyzer is configurable via the `vs-threading.LegacyThreadSwitchingMembers.txt` file.