Update documentation throughout the project

tracing/doc.go

@@ -0,0 +1,8 @@
+// Package tracing provides helpers and bindings for distributed tracing.
+//
+// As your infrastructure grows, it becomes important to be able to trace a
+// request, as it travels through multiple services and back to the user.
+// Package tracing provides endpoints and transport helpers and middlewares to
+// capture and emit request-scoped information. We use the excellent OpenTracing
+// project to bind to concrete tracing systems.
+package tracing