define project-name attribute before document title to fix a warning in Asciidoctor 2

[mojavelinux]

I think the problem is that this attribute is used in the page title, and some places in the Antora pipeline don't support that use case unless the attribute is defined in the component descriptor. This is the best short-term fix.

[slonopotamus]

I'm not sure what warning you're talking about, but I am ready to merge this if you say it is a good thing :) Actually, there's no reason to use attribute in page title, I can easily make it just text.

[mojavelinux]

I went looking for it and it appears to be a regression caused by the upgrade to Asciidoctor 2 in Antora (currently in Antora 3.0.0-alpha.3). Either that, or Asciidoctor 2 detects an unresolved attribute reference somewhere Asciidoctor 1 does not. I narrowed it down to this page in Asciidoctor EPUB3, but I'm not sure yet why. I'm investigating.

Here's the reference: https://app.netlify.com/sites/asciidoctor-docs/deploys/607960b4b1f74d00071fd4ca#L64-L65

[mojavelinux]

I've determined this is a bug (or bug-ish) in Asciidoctor. I'm going to address it there. It shouldn't require a change to the content. Though, if you really want the most accurate fix, I've updated the PR to show what that would be.

[mojavelinux]

Here's the related issue in core: asciidoctor/asciidoctor#4024

[slonopotamus]

We can define attributes before document title? o_O My world will never be the same.