Add reference to rename endpoint in correct version & add to new

Docker-DCO-1.1-Signed-off-by: Jessica Frazelle <jess@docker.com> (github: jfrazelle)

docs/sources/reference/api/docker_remote_api.md

@@ -56,6 +56,11 @@ Docker client now hints potential proxies about connection hijacking using HTTP
 **New!**
 This endpoint now returns the list current execs associated with the container (`ExecIDs`).
 
+`POST /containers/(id)/rename`
+
+**New!**
+New endpoint to rename a container `id` to a new name.
+
 ## v1.16
 
 ### Full Documentation