I'm a CTO in a startup and all our docs are in .md files, mermaid diagrams with dynamic Table of Content generation.
We have two repos: Product (to anything relating to product) and Wiki (anything else, ranging from onboarding checklists, brief design documentation of key parts of the code ... to meta documentation)
Although our team is small by many standards (8) everyone likes it.
We spend a ridiculously small amount of time on meetings.
The obvious and great upside is the code/documentation integration which has virtually 0 context loss.
One downside however is indeed the difficulty of git branching to non-developers.
Once in while I find myself debugging a messed up version.
