Add a manual page

[andrewshadura]

Hi,

I wrote a manual page since ckati currently lacks one. It is not 100% complete and it is missing some options, so I’m sure you can improve it, but I tried to cover the options I hope are the most useful.

I wasn’t sure whether I should commit only the Markdown source or also the generated file, so I committed both; please let me know if you’d like only the source file. The roff file is generated with pandoc, but I can change it to something else if you prefer.

I have signed the CLA already.

[KOLANICH]

@andrewshadura, I have also created a manual page, but my one is a bit poor - it completely lacks most of extensive human-written text. I have taken a bit different approach.

1. First I have implemented --help and CLI args parsing using CLI11. Unfortunately it hasn't beeen merged, I was just said that they don't want a dependency on CLI11.
2. So second I have implemented the bit same. I have an own branch with CLI11, I output --help into a file, and that file is included within a string literal and just printed as a help message. Not so good solution as a native CLI11, but better than no help message at all and better than fully hand-crafted help message. The drawback is that I have to maintain an own fork of CLI11 branch.
3. Then I used help2man to generate a manpage stub.

I wonder if a generated manpage stub can be combined with a handwritten one automatically to generate a manpage combining the advantages of both.

[andrewshadura]

@danw, could you please have a look?

[andrewshadura]

@lberki, maybe you could have a look?