Quick README update to note the versioning policy

nblumhardt · nblumhardt · commit 6be97a718ebb · 2023-05-03T18:53:12.000+10:00
diff --git a/README.md b/README.md
@@ -428,3 +428,7 @@ In order to make auto-discovery of configuration assemblies work, modify Functio
 
 </Project>
 ```
+
+### Versioning
+
+This package tracks the versioning and target framework support of its [_Microsoft.Extensions.Configuration_](https://nuget.org/packages/Microsoft.Extensions.Configuration) dependency.
