Update Dockerfile

1 job for master in 1 minute and 52 seconds (queued for 6 seconds)
Name Stage Failure
build-docker-master Build
'build/index.html' -> 'public/index.html'
Removing intermediate container 77a2c09a785a
---> 2b4ba5addb41
Step 8/9 : RUN cp /app/public/ /usr/local/apache2/htdocs/
---> Running in 88830f0c782b
cp: -r not specified; omitting directory '/app/public/'
The command '/bin/sh -c cp /app/public/ /usr/local/apache2/htdocs/' returned a non-zero code: 1
Cleaning up project directory and file based variables
ERROR: Job failed: exit code 1