Please document that error 404 could also mean an empty list

[cipherboy]

As reported by @stormshield-gt on hashicorp/vault#25969:

When using a list endpoint, if there is no item to list, the API returns an error 404.

As explain here, this unusual behavior is kept for backward compatibility. The original rational can be found here #1365

This has been a painful point for users since a long time, as we can see by the number of related issues #20740 #13043 #24964 #1958 #5861 #8833 hvac/hvac#928

I think this will keep hurting users, again and again, if the behavior continues to be undocumented.

I suggest updating the documentation about the error codes returned by the API to mention that 404 could also mean an empty list.