feat: Allow setting bound host in serve with -H

[CircuitCoder]

This commit adds a switch --host / -H to the serve subcommand, allowing user to choose which address to bind on.

Also, by introducing a default value of "localhost", now the default behavior of serve is that the site is only accessible on the localhost. This is more secure, and more in line with the original console output, but can be a somewhat minor breaking change.

Fixes#230

[sy-records]

Thanks!

We will release version v5 later, so this is not a major change and is acceptable.

Could you please update the README.md and docs/README.md files to include this content?

[CircuitCoder]

update the README.md and docs/README.md files to include this content?

Added in 7be3806 :)