Update license information for tap specifications

[bjh83]

The TAP specifications state that they are licensed under the "same
terms as Perl itself" and then provide a link which is out of date. This
change updates the link to a valid copy of the Perl artistic license,
adds SPDX identifiers at the top of the specifications, and adds a copy
of the Perl artistic license to the repository.

Why add a copy of the license and SPDX identifiers? It turns out that
there are multiple revisions of the Artistic License 1.0; the copy of
the license and the SPDX identifiers make it explicit which version of
the Artistic License 1.0 is used.

I only added the SPDX identifiers to the two TAP specifications because those were the only two files that were clearly labeled as being under the Artistic License; however, I can add the identifier to other files if people like.

Side note: the Artistic License 1.0 has been superseded by Artistic License 2.0, we might want to update that in a subsequent change.

[bjh83]

Ping.

I would like to "fork" the TAP specification for a project that I am working on (the Linux kernel). I am using the proposed TAP 14 spec now, but given that the TAP 14 PR hasn't been accepted and that there doesn't seem much motivation to do this right now, I would just like to copy the TAP spec into the project directly, so that we don't have to worry about this changing underneath us.

In order to do so, I need to make sure we are obeying the terms of this project's copyright.

If there is anything I can do to make this smoother, please let me know.

Cheers

[mblayman]

Thanks for the contribution. I believe this branch is making the license more explicit so I see no problem with the substance.

From an implementation point of view, I'm not sure the PR can be accepted as is. The testanything.org website is generated via Jekyll. My interpretation of the frontmatter section is that it must appear before anything else (see https://jekyllrb.com/docs/front-matter/).

Can you move the HTML comment identifiers so that they appear after the frontmatter for the spec files?

[kinow]

Looks good to me. I've also added a note in #164 to see if we can add the same header to the TAP 14 specification, but using artistic license 2.0.

Or maybe moved to a Markdown comment (going along @mblayman 's comment above).

Thanks

[isaacs]

Yeah, this looks fine, but the comment has to come after the Jekyll frontmatter.

Happy to land it with the necessary edit, it's straightforward.