add a direct example for changing the cmd that is run
add example for docker rmi, and explain the need to remove all references (tags) to and image before its garbage collected :)
Corrected typo (resdis -> redis)
Merge pull request #3162 from SvenDowideit/docker-commit-example-change-CMD

add a direct example for changing the cmd that is run
Merge pull request #3165 from SvenDowideit/cmd-rmi-example

add example for docker rmi, and explain the need to remove all references (tags) to and image before its garbage collected :)
Merge pull request #3167 from qbrossard/patch-1

Corrected typo (resdis -> redis)