readTimeout is a new setting for traefik as of v2.11.2

I spent a lot of time tracking down why my setup was timing out on large file uploads (knowing it was working several months ago), and finally landed on this being the cause. Specifically, during my workbench ingest jobs the uploads were failing with

499 Client Closed Request' caused by: context canceled

Bumping this value beyond the default 60s got rid of the error.

I think we should consider setting this value in one place. Maybe NGINX_PROXY_READ_TIMEOUT and using the value for both traefik and nginx/drupal. At the minimum, set this in docker-compose.yml with a comment and also update https://islandora.github.io/documentation/user-documentation/uploading-large-files/