* Add new/updated docs for [Behind a Proxy](https://fastapi.tiangolo.com/advanced/behind-a-proxy/), including how to setup a local testing proxy with Traefik and using `root_path`.
    * Update docs for [Extending OpenAPI](https://fastapi.tiangolo.com/advanced/extending-openapi/) with the new `openapi_prefix` parameter passed (internally generated from `root_path`).

Koan-Sin Tan, lingzhi98, looi, Mahmoud Abuzaina, Malik Shahzad Muzaffar, Meekail Zain, mraunak, Neil Girdhar, Olli Lupton, Om Thakkar, Paul Strawder, Pavel Emeliyanenko, Pearu Peterson, pemeliya, Philipp Hack, Pierluigi Urru, Pratik Joshi, radekzc, Rafik Saliev, Ragu, Rahul Batra, rahulbatra85, Raunak, redwrasse, Rodrigo Gomes, ronaghy, Sachin Muradi, Shanbin Ke, shawnwang18, Sheng Yang, Shivam Mishra, Shu Wang, Strawder, Paul, Surya, sushreebarsa, Tai Ly, talyz, Thibaut Goetghebuer-Planchon, Tj Xu,...