Update README.md

增加一点可能出错的提示

Author: dforel

README.md

@@ -114,6 +114,10 @@ Edit line 16 to point to your relay server (the one listening on port 21117). Yo
 
 (docker-compose credit goes to @lukebarone and @QuiGonLeong)
 
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+Note that here, the rustdesk/rustdesk-server:latest in China may be replaced with the latest version number on dockerhub, such as rustdesk-server:1.1.10-3. Otherwise, the old version may be pulled due to image acceleration.
+注意，这里的rustdesk/rustdesk-server:latest可能在中国大陆区域内换成dockerhub上的最新版本号，比如rustdesk-server:1.1.10-3，否则可能因为镜像加速的原因拉取到落后的版本。
+
 ## S6-overlay based images
 
 These images are build against `busybox:stable` with the addition of the binaries (both hbbr and hbbs) and [S6-overlay](https://github.com/just-containers/s6-overlay). They're available on [Docker hub](https://hub.docker.com/r/rustdesk/rustdesk-server-s6/) with these tags: