Our team of approx 60 devs are using Atlassian Confluence. The choice was really simple, since we had an existing wiki, and our company moved to the Atlassian suite of products.
We've also focused on documentation that describes behaviours of systems and across systems. So most of it actually reflects what the intent of the code is. Capturing intent and being able to track decisions / choices and motivations over time has allowed us to actually have useful documentation that allows the next developer / tester / ops / whoever to get up to speed relatively quickly.
It's also a wonderful source of group decisions / goals when starting projects, that give a lot of context into why code has been written in a certain way.
I'm not a huge Jira fan, but Confluence is super easy, straight forward, and quite intuitive in comparison.
We have tried with google docs, but that's never worked well enough. too ad-hoc, hard to navigate and discover things in the structure, and... It almost hurts to say it...Confluence has great Jira integration that makes life easier for us 😁
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