Output colors not available when running from Docker image

[aureliojargas]

We have colors when running non-Docker and when running inside Docker in an interactive session:

$ ./clitest -L -t 1 test.md
#1  test -f ./clitest; echo $?

$ docker run -it aureliojargas/clitest sh 
/ # cd /app && ./clitest -L -t 1 test.md
#1  test -f ./clitest; echo $?

But no color when running non-interactive:

$ docker run aureliojargas/clitest sh -c 'cd /app && ./clitest -L -t 1 test.md'
#1  OK  test -f ./clitest; echo $?

[aureliojargas]

You must use docker run -t to make sure Docker can allocate a pseudo-TTY and show colors.

[aureliojargas]

Closing this one, since now it's properly documented in the README-docker.md file.