Yesterday we had another discussion about architecture documentation and especially about decisions made about it. We came to a quick agreement, that the form makes no difference, but that there is a dire need for a way to see, why something is like it is.
One of the tooling suggestions here is ADR (repo), which basically is just a helper for easy to handle markdown files, which can either be placed next to the code (for microservices) or into a dedicated repository. (for macroarchitecture)
I am always in favor to have docs next to code, so the chance that a) someone really reads it and more importantly b) keeps it up to date is better. From my experience a wiki is just a collection of outdated files: Barely read; never updated.
Now that we have nice tools for our handiwork, we have to think about who writes docs and first and foremost when?
The latter is really easy, whenever a decision is made like which technology stack, which testing framework and so on, just write an entry.
And the answer to the first question? Probably you!