Tracing rewrite

CHANGELOG.md

@@ -1,5 +1,28 @@
 # CHANGELOG
 
+## v13.0.0
+
+## Breaking Changes
+
+The `tracing` package has been rewritten to provide a common interface for consumers to wire in the tracing package of their choice.
+What this means is that by default no tracing provider will be compiled into your program and setting the `AZURE_SDK_TRACING_ENABLED`
+environment variable will have no effect.  To enable this previous behavior you must now add the following include to your source file.
+```go
+  include _ "github.com/Azure/go-autorest/tracing/opencensus"
+```
+The APIs required by autorest-generated code have remained but some APIs have been removed and new ones added.
+The following APIs and variables have been removed (the majority of them were moved to the `opencensus` package).
+- tracing.Transport
+- tracing.Enable()
+- tracing.EnableWithAIForwarding()
+- tracing.Disable()
+
+The following APIs and types have been added
+- tracing.Tracer
+- tracing.Register()
+
+To hook up a tracer simply call `tracing.Register()` passing in a type that satisfies the `tracing.Tracer` interface.
+
 ## v12.4.3
 
 ### Bug Fixes