Add changelog for Gin transaction name update.
# ChangeLog
+### Changes
+
+* Use
+ [`Context.FullPath()`](https://godoc.org/github.com/gin-gonic/gin#Context.FullPath)
+ for transaction names when using Gin version 1.5.0 or greater. Gin
+ Transactions were formally named after the
+ [`Context.HandlerName()`](https://godoc.org/github.com/gin-gonic/gin#Context.HandlerName)
+ which uses reflection. This change both improves transaction naming and
+ overhead. Please note that because your transaction names will change, you
+ may have to update any related dashboards and alerts to match the new name.
+
+ ```go
+ // Transactions previously named
+ "GET main.handleGetUsers"
+ // will be change to something like this match the full path
+ "GET /user/:id"
+ ```
+
## 3.3.0
### New Features
