Tidy up specification for point release

[jemrobinson]

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⤴️ Summary

• Add links to business process/application component/data object glossary definitions
• Tidy up second-level headings
• Add numbering

🌂 Related issues

🙋 Acknowledging contributors

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[JimMadge]

I don't like the DIY subsections using bold text for each capability component. Using headings gives us styling and cross referencing for free. This was moves burden to us to keep the style consistent and create labels where we need them.

What is the problem with using headings?

(I'm glad we got rid of the italic paragraphs though 🧐)

[jemrobinson]

What is the problem with using headings?

With our current settings ({toctree} :numbered:), headings get automatic numbering. We don't want capability components to have numbers. If you'd prefer, I can remove this setting and add manual numbers but restore the capability component as headings.

[jemrobinson]

@sa-tre/spec-maintainers: we should get whatever style changes we decide on merged by the end of the day so we can tag v0.3 and start evaluating against it.

[JimMadge]

@jemrobinson We should be able to give an argument to :numbered: to set what level to number headings to.

I think here we want :numbered: 2.