Add a good example of `doing-cli` to main github page

[operte]

The main github page doesn't do a good job convincing people why doing-cli can be useful. We could add e.g. one of the examples in the main documentation page https://ing-bank.github.io/doing-cli/

[RamiSJ12]

I find these are certin line that can be doing good job but need for extentions or outsourse