The fix for that is to keep the documentation in the same repository as the code it documents, and then to enforce that it gets updated as part of your code review process. Don't let a PR land if it doesn't also update any relevant documentation at the same time.
Keeping documentation in a separate system - like a wiki - is an anti-pattern in most cases. It leads to documentation that nobody trusts (and hence nobody consults) because it inevitable falls out of sync with the system it is documenting.
Plus... LLMs are good enough now that having one automatically check PRs to warn if the change affects the existing documentation might actually work well enough to be useful.
Keeping documentation in a separate system - like a wiki - is an anti-pattern in most cases. It leads to documentation that nobody trusts (and hence nobody consults) because it inevitable falls out of sync with the system it is documenting.
Plus... LLMs are good enough now that having one automatically check PRs to warn if the change affects the existing documentation might actually work well enough to be useful.