Doxygen Refresh

[jackoalan]

Athena has changed considerably since the doxygen comments were last updated.
Several APIs (notably the DNA and YAML classes) have no docs at all.

This issue tracks the refresh/update of these docs starting from 2.4.0 release.

[Antidote]

We should start by documenting the DNA structs, since those are completely devoid of them. Then we'll use that as our new document standard.

[jackoalan]

Agreed, we can also fill up the org's Jekyll site with usage examples

[Antidote]

Yeah, Jekyll should provide usage examples, while the doxygen should simply document use cases in general.