Add man page for the command-line utility

[sorairolake]

I think this is useful for understanding the detailed usage of the command-line utility.

[TPS]

Probably should be done concurrently w/ #472.

[g0blin-NN]

oxipng --help > oxipng.txt

[TPS]

Given so many recent updates (most of which haven't merged, much less released), I'm not aware whether even the command-line help is current.

[g0blin-NN]

Even like this? Sorry.
Although in version 6.0.0 they added.
[Feature] Add --check/-c CLI option
is present in --help. They didn't add anything else.

[TPS]

I vaguely remember a discussion someplace in these Issues re: how out-of-date the --help is, & another PR recently (merged? 🤷🏾‍♂️) that is supposed to (partially? 🤔) solve that.

[andrews05]

--help has been kept up-to-date with all changes, it's just the Read Me that may be out of date.

@sorairolake Not saying there shouldn't be a man page, but was there something in particular you were wanting to understand that wasn't explained sufficiently in --help?

[sorairolake]

@andrews05 I also think the usage in --help is explained sufficiently. However, I think it would be more useful to be able to see how to use oxipng on the web (such as https://man.archlinux.org/) or a console.

[andrews05]

One easy thing we could do is append the help output to the Read Me (in some sort of automated fashion). This would at least make it easily accessible online.

[musicinmybrain]

You might (or might not) find clap_mangen (GitHub, crates.io) useful for this.

If you want to maintain a hand-written man page, I am happy to contribute one based on the current --help output.

[andrews05]

Thanks @musicinmybrain, see #596 where I’m using that 🙂
I hope to pick it up again soon and see if I can make a deb package…