Added manpage for magic-wormhole

[werdahias]

Closes: #145

[piegamesde]

I think I'd prefer a generated man page, as that should be better for long-term maintenance. Without at least some tooling yelling at you, it's too easy to modify the CLI options and then forget about the man page.

[felinira]

I agree. I want to get 0.7 out rather soon so I'll get this in as is, but I opened #231 to track this.

[felinira]

@werdahias I missed this:

Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU General Public License, Version 3 or (at your
option) any later version published by the Free Software Foundation.

Are you willing to relicense the man page to EUPL, as is the rest of this repo? Otherwise I would need to remove it again.

Licensing it under GPL is would prevent us from actually redistributing this.

[werdahias]

Sure, do you need me to push a relicensed version?

[felinira]

That'd be ideal because it signals approval (otherwise I can link to this discussion in the commit.)

The required notice is simply

Licensed under the EUPL