This is too biased for-docs IMHO*. I do agree with many points, documentation IS amazing, and you are very likely under-documenting things in your company. But documentation is not cheap to create, and specially it's not cheap to maintain. If you are not writing enough yes, sure, that's probably a great investment, but start bit by bit.
I've worked in multiple* companies where the problem was too much documentation, and of course everyone was afraid to update or ghasps* remove any piece of old documentation in case it was still useful. Imagine working on a codebase where 80% of the code was unused or commented out but no one dared changing it just in case (flashback to 2010 with 4000 lines of style.css).
I'd suggest to take a more holistic approach and treat documentation a lot like testing; for that prototype, probably just write the barebones documentation, for the production-ready new feature go all-in and write detailed documentation, tutorials, etc.
If you do want to go deeper with documentation, then you'll need a dedicated team (like a team of testers) that work exclusively on documentation. At some point it does make sense to hire only for that, and it can even be a differentiating point for your startup if done correctly.
For libraries, a ratio I've seen works pretty well is approx 1:3:5 for lines of code:tests:docs; you can do tests first, or even documentation first, but once everything is finished and if you count the amount of lines that's a decent ratio. Note that when counting "lines of docs" in an editor, a whole paragraph will count as just 1, so in reality there's a lot more docs.
Note: I'm the creator of both https://documentation.page/ and https://documentation.agency/
* (only 2 "negative" paragraphs on a book-length article)
I've worked in multiple* companies where the problem was too much documentation, and of course everyone was afraid to update or ghasps* remove any piece of old documentation in case it was still useful. Imagine working on a codebase where 80% of the code was unused or commented out but no one dared changing it just in case (flashback to 2010 with 4000 lines of style.css).
I'd suggest to take a more holistic approach and treat documentation a lot like testing; for that prototype, probably just write the barebones documentation, for the production-ready new feature go all-in and write detailed documentation, tutorials, etc.
If you do want to go deeper with documentation, then you'll need a dedicated team (like a team of testers) that work exclusively on documentation. At some point it does make sense to hire only for that, and it can even be a differentiating point for your startup if done correctly.
For libraries, a ratio I've seen works pretty well is approx 1:3:5 for lines of code:tests:docs; you can do tests first, or even documentation first, but once everything is finished and if you count the amount of lines that's a decent ratio. Note that when counting "lines of docs" in an editor, a whole paragraph will count as just 1, so in reality there's a lot more docs.
Note: I'm the creator of both https://documentation.page/ and https://documentation.agency/
* (only 2 "negative" paragraphs on a book-length article)