I have been on many development teams and as the team matures decisions about direction are made. These decisions often come back up over and over. Like why don't we fill in this field why didn't we use memcache over a custom solutions. These decisions add up over time and become a significant part of style guides coding standards and unit tests.
My question is I have never run into a good way of tracking these decisions or the discovery that went into making them. Does anyone have a best practice.