Update Dockerfiles

[krbrs]

Remove obsolete webui volume as it's in the already exported home directory - if I'm not wrong.

This should solve:

• QNAP Container Station keeps bugging to map it to a volume or share
• Portainer creating an empty volume

[revam]

Personally i don't mind keeping or removing the volume.

@da3dsoul @Cazzar thoughts on removing it?

[Cazzar]

There’s your answer @revam