Remove title heading and automatic see-also section

[amartini51]

Fixes #6

[krilnon]

I'll test this with a recent DocC toolchain soon. In the meantime, it looks like this turns off the Article title headings; did we want to test out @TitleHeading("Chapter") as well? (Perhaps in a subsequent issue.)

[amartini51]

Changing the title heading to "Chapter" seems reasonable to me — if we like that better, I'm fine doing it all on this PR.

[bjlanier]

@SamLanier what are your design thoughts on using "Chapter" for the title headings instead of the default "Article"?

[SamLanier]

I think both options could work. I'm not sure a title heading (eyebrow) makes the most sense to label the chapters (we currently use eyebrows to convey the content type, and the reason for hiding those eyebrows would be that the content type is assumed to be the same). That said, there's nothing wrong with using the eyebrow as a chapter heading temporarily until another solution would be better. For example, being able to see a TOC of all the chapters might be more useful to the reader than an eyebrow shown on the chapter you have already selected.

[amartini51]

Here's a screenshot of what TSPL looks like without the title headings (this PR's change), with chapter abstracts added, and built with current DocC main.

[krilnon]

@swift-ci please test