Update CHANGELOG

Author: XSAM

CHANGELOG.md

@@ -17,7 +17,8 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 - Unify instrumentation about provider options for `go.mongodb.org/mongo-driver`, `gin-gonic/gin`, `gorilla/mux`,
   `labstack/echo`, `emicklei/go-restful`, `bradfitz/gomemcache`, `Shopify/sarama`, `net/http` and `beego`. (#303)
-- Update instrumentation guidelines about uniform provider options. (#303)
+- Update instrumentation guidelines about uniform provider options. Also, update style guide. (#303)
+- Make config struct of instrumentation unexported. (#303)
 
 ## [0.11.0] - 2020-08-25