Document write option in a better way

[schultyy]

Right now it's not 100% obvious what needs to be passed to -w as an argument. The help text says (default: yes if CI is set, otherwise no). but it took me some time to figure that out after looking at it after some time.
My proposal would be to explicitly say what needs to be passed for the W param here:

  -w W, --write=yes/no        Write changes to files (default: yes if CI is set, otherwise no).

We need to check what docopt actually allows here as valid values.

This should also be mentioned in the README as well.

[emig]

I see the following alternatives to that command, not using arguments:

• -y
Yes (without argument). Authorize potentially destructive actions for which the program would normally require confirmation. Examples: fsck(1), rz(1). this idea is taken from http://catb.org/~esr/writings/taoup/html/ch10s05.html and follows over time, frequently-used options in well-known Unix programs.
• -w --write (without argument)