[Other] Reference to paperless-ngx in docs

[royalroot]

Hi,
first of all let me thank you for your good work.
I have tons of docs now in paperless.

But before you get any more issues here I just wanted to point you to paperless-ngx which is an active fork of your work.

Maybe you find the time to mention this project in your docs so no one starts with a dead project without updates.

I'm not a developer or contributer but I wanted to tell you this.
Have a nice day,
Nico