[docs] document how to put phoenix behind a reverse proxy

[mikeldking]

Add a section in self-hosting to show how to put phoenix behind a reverse proxy by configuring a root path

[mikeldking]

@Jgilhuly feel free to assign out.

[dosubot[bot]]

Hi, @mikeldking. I'm Dosu, and I'm helping the Arize Phoenix team manage their backlog and am marking this issue as stale.

Issue Summary:

• You requested adding documentation in the self-hosting section about configuring Phoenix behind a reverse proxy with a root path.
• The goal is to assist users in properly setting up Phoenix in such environments.
• You invited @Jgilhuly to take on the task.
• There have been no further updates or discussions since your initial request.

Next Steps:

• Please let me know if this issue is still relevant to the latest version of Arize Phoenix by commenting here.
• If I don’t hear back within 7 days, this issue will be automatically closed.

Thanks for your understanding and contribution!