We use the concept of Architecture Decision Records (ADRs) to document the decisions that we make in the development of the PlatformPlatform project.
An Architecture Decision Record is a short text file in a format that makes it easy to compare different decisions. Each record describes a set of forces and a decision in response to those forces. The decision is the answer to the question: "What is the best way to address these forces?"
We use the standard format for ADRs as described in the Architecture Decision Records website.