I tried to create this type of culture at my last gig, where I had the unusual privilege of being able to hire almost the entire engineering team, alongside my manager who was also very document oriented. Unfortunately, it didn't work out. Maybe Tremendous has done tremendously better, it's certainly possible, but here is a list of things that went wrong, maybe it's useful.

1. Standard interviews don't assess reading/typing speeds. If you want a high documentation culture this is critical. It took way too long for us to figure this out but many people in the company were significantly slower at reading/typing than us; they found long documents overwhelming and would find excuses to not read them. Slack conversations became a massive sore spot because unknown to us some people felt like they couldn't keep up. They'd try to type a question or response and we'd already posted another two paragraphs before they got a chance to finish their thought. They'd complain to each other that if they asked us a question they got back an essay in response, etc.

2. Documentation requires ownership, otherwise it rapidly becomes useless. Standard corp tooling like wikis doesn't make such workflows easy. They are however optimal from a corp politics perspective (dispersal of responsibility). Maintaining markdown based websites works well as long as you have empowered maintainers who view document quality as a core job function, but you have to force people to submit changes by e.g. rejecting at code review time changes that don't update the docs. People will moan. They will ask you to do it for them. They will submit absolutely min-viable docs changes, they will demand you hire technical writers even if they're easily capable of doing it themselves. And of course the moment you're not using a git-style workflow, just forget it, you have no chance of preserving coherency in any sort of knowledge base.

3. Lots of people aren't just slow but actively HATE reading and writing. They will make things up on the spot, or lie, or just flat out refuse to do the work rather than sit down and read a long document. Jeff Bezos has said about why Amazon uses meeting time to force people to read the memo:

"If we don’t, the executives, like high school kids, will try to bluff their way through a meeting"

You will have to fire people for refusing to read things if you're serious about creating and maintaining such a docs-oriented culture, which in practice is so unpleasant nobody ever does it and so maintaining such a culture is nearly impossible. You will also have to flat-out refuse to meet people in order to force them to read, because otherwise they'll receive a document and just ignore it. I had several cases where one of my most senior engineers would assert that a product we used didn't have feature X, and I had to correct him by pointing out that the user manual discussed feature X in detail. I knew this because I'd actually read the user manual cover to cover. Basically nobody does this and guess what, if you're the one person on the team who reads stuff then you're going to come across as the awkward smart alec who makes people look stupid. Sometimes, ignorance is bliss.