docs: add goatcounter to sphinx documentation footer
docs: add goatcounter to sphinx documentation footer

I want to have some way to have any idea whether anyone actually reads this documentation, to guide me on whether it's worth maintaining. Hopefully goatcounter is a reasonable compromise - it doesn't collect any personal information, it just counts visitors with a couple of non-identifying attributes like screen type and region.

jelford/activesoup,jelford/activesoup,jelford/activesoup