Generate CLI docs more flexibly with cog

[sgraaf]

It might be worthwhile to replace sphinx-click with cog in order to automatically generate CLI docs (and possibly also generate documentation in other places). For a reference implementation, see this Twitter thread or https://github.com/simonw/sqlite-utils/commit/1d44b0cc2784c94aed1bcf350225cd86ee1aa7e5.

Some possible advantages of the top of my head (I am sure there are others):

• With cog, you have (near-)infinite degrees of freedom when it comes to customizing the output of the generated CLI documentation
• cog is a more general tool that could also be used in other parts of the template
• By removing a Click-related dependency, you also reduce this template's dependency on Click itself

I'd appreciate hearing your opinion on this. If you approve, I would be happy to take up this issue. 😀