Maybe document subfolder based access (example)

[joshtrichards]

There's a distinction between a subfolder installation of Nextcloud (i.e. somewhere under the docroot) and merely making Nextcloud reachable via a subfolder style URL (https://domain.tld/nextcloud). The former is not something relevant to this image, while the latter is a config matter (including reverse proxy integration)

There's probably an opportunity to improve upstream documentation and/or our docs & examples here at the Docker level.

I mention this so that maybe we can finally close out the following issues:

• Run Nextcloud from Subdirectory #401
• Trick to run docker nextcloud fpm with nginx in a sub directory #1919
• Using the fpm image in a subdirectory of the proxy #2187
• Question: NextCloud available in subfolder #1047