Improve documentation and add manpages

[groenborg]

I would like an improved doc and man page for the commands so it is easier for the users to use the CLI.

The current explanations may be outdated and quite vague. A deeper explanation and examples in man pages will greatly benefit the project and usage.

Documentation can be found here: https://github.com/spf13/cobra/blob/master/doc/man_docs.md