[WIP] Document limitation using veth pairs between containers

[Copilot]

• Review parent issue Both sides of a VETH pair can not be assigned to containers #941 to understand the limitation
• Add limitation documentation to container.md in appropriate sections
• Add limitation description in YANG model (infix-if-container.yang)
• Review and verify changes

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Document limitation using veth pairs between containers</issue_title>
<issue_description>See parent issues</issue_description>

Comments on the Issue (you are @copilot in this section)

@jovatn Document in yang and container.md.

• Fixes Document limitation using veth pairs between containers #947

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.