#1665 improve Docker docs

docker/README.md

@@ -41,7 +41,7 @@ Most of settings are obvious and easy to understand, but there are some settings
 
 - **Repository Root Path**: keep it as default value `/home/git/gogs-repositories` because `start.sh` already made a symbolic link for you.
 - **Run User**: keep it as default value `git` because `start.sh` already setup a user with name `git`.
-- **Domain**: fill in with Docker container IP(e.g. `192.168.99.100`).
+- **Domain**: fill in with Docker container IP(e.g. `192.168.99.100`). But if you want to access your Gogs instance from outside world, please fill in with corresponding public domain or IP address.
 - **SSH Port**: Use the exposed port from Docker container. For example, your SSH server listens on `22` inside Docker, but you expose it by `10022:22`, then use `10022` for this value.
 - **HTTP Port**: Use port you want Gogs to listen on inside Docker container. For example, your Gogs listens on `3000` inside Docker, and you expose it by `10080:3000`, but you still use `3000` for this value.
 - **Application URL**: Use combination of **Domain** and **exposed HTTP Port** values(e.g. `http://192.168.99.100:10080/`).