improve security doc for model security check

[lxning]

📚 The doc issue

The model url provided by cx potentially can contain unsafe content. Existing security lacks the summary of guidance to cx to overcome this issue.

Suggest a potential alternative/fix

TorchServe provides 3 different levels security check to address this issue. TorchServe Security doc can be updated to provide guidance for cx.

• option1: allowed urls
• option2: cx plugin is a flexible solution which allows cx to add the security check they prefer.
• option3: prod infra (cloud service or internal company infra) provide AOT security check.