docs: migrate.md adjust volume mount path

[francislavoie]

The rest of the examples use /var/www/app, so the volume mount should match.

[henderkes]

Oh, great catch, but the image defaults to /app. We'll need to adjust all other occurrences instead :/

[henderkes]

Meh, Claude isn't getting it right. I'll just do it...

[henderkes]

The default path isn't /var/www/app for the nginx image either, so it's fine just overwriting the config for our example like we do in the nginx one.

[francislavoie]

Generally we recommend mounting a directory rather than a file because certain methods of editing files don't correctly get followed by a bind mount (if the inode swaps or w/e, I think).

So it should be more like this:

Suggested change

	- ./Caddyfile:/etc/frankenphp/Caddyfile
	- ./config:/etc/frankenphp

Where the Caddyfile is at ./config/Caddyfile.

Also this lets users have more config files that get imported in chunks.

Covered here https://caddyserver.com/docs/running#docker-compose

[henderkes]

The reason why I added this is for parity with the nginx example above, so when the nginx example mounts in the single file, the frankenphp example should, too. Or we change it for both. This is really for a minimal configuration where multiple files aren't needed (typically the app-level Caddyfile is meant to run standalone, isolated, anyhow).

[francislavoie]

I get that, but it's a well-known footgun where if you edit the Caddyfile with vim then try to reload it will not work if you mounted it this way. (Works fine if you used nano, it saves the file with the same inode)

[henderkes]

Let's change it for both then.