Update README.md

Signed-off-by: Eundoo Song <eundoo.song@gmail.com>

Author: eundoosong

examples/hotrod/README.md

@@ -49,10 +49,11 @@ go run ./main.go all
 docker run \
   --rm \
   --link jaeger \
+  --env JAEGER_AGENT_HOST='jaeger' \
+  --env JAEGER_AGENT_PORT=6831 \
   -p8080-8083:8080-8083 \
-  jaegertracing/example-hotrod:1.6 \
-  all \
-  --jaeger-agent.host-port=jaeger:6831
+  jaegertracing/example-hotrod:1.8 \
+  all
 ```
 
 Then open http://127.0.0.1:8080