Add SPDX tags to example manual pages in share/examples/mdoc/

[0mp]

Summary

I thought that it might be useful to have the SPDX tags included in the examples of manual pages.

I also added an SPDX tag to share/examples/mdoc/POSIX-copyright. It's worth noting that the link referenced in the POSIX-copyright file is dead (http://www.opengroup.org/unix/online.html).

[0mp]

This comment was removed by 0mp.

[imp]

You'll need to rebase after my push. Sorry.

[0mp]

Rebase diff after D15264: Remove 'All Rights Reserved' from the collection copyright and templates..

[sevan]

Re opengroup link. The earliest archived version on archive.org is from 1999 & that redirects to http://www.UNIX-systems.org/online.html, Not sure where to fish out the IEEE Std 1003.1, 2004 Edition details from there though.

[eadler]

examples/mdoc/POSIX-copyright

2 ↗

(On Diff #42302)

This is a little different since it includes POSIX references, but I'm not sure that's part of the copyright.

[0mp]

examples/mdoc/POSIX-copyright

2 ↗

(On Diff #42302)

Should I skip it for the time being?

[0mp]

Reupload the patch using Arcanist.

[mat]

Seems to have been accepted by a docs committer, so ok.