fix: Dockerfile vanity COPY

[SpeedyFireCyclone]

The current COPY directives in the Dockerfile that add the vanity files have an unintended trailing asterisk, causing only root.xml's contents to be in there under the filename '*'. This is obviously unintendend as this causes the vanity to be non-functional in the default docker setup.

[EmosewaMC]

Thanks for spotting this and submitting a fix!