Optionally generate pages for taxonomies (tags, categories, etc)

[mntn-xyz]

https://gohugo.io/content-management/taxonomies/

I'd suggest duplicating the Hugo defaults, and using the defaults (tags/categories) OR the list from [taxonomies] if present, plus any exclusions from [disableKinds]. This could probably be handled in the same way as baseUrl and title, where overrides can be established in the [gmnhg] section.

Taxonomy index templates would be passed a list of pages with metadata, just like an index page.

I'll probably work on a PR for this when I have some free time.

[tdemin]

Probably even more important for a Gemlog than for a weblog due to having much less reliance on search engines and page metadata.