docs: revise Docker usage instructions in README (#2882)

Updated Docker instructions for HugeGraph server.

Author: imbajin

README.md

@@ -37,8 +37,7 @@ Use Docker to quickly start a HugeGraph server with `RocksDB` (in the background
 
 ```
 # (Optional) 
-# 1. remove "-e PASSWORD=xxx" to disable the auth system
-# 2. add "-e PRELOAD=true" to auto-load a sample graph
+# - add "-e PRELOAD=true" to auto-load a sample graph
 docker run -itd --name=graph -e PASSWORD=xxx -p 8080:8080 hugegraph/hugegraph:1.5.0
 ```