Despite the abundance of research on methodologies for the documentation of design decisions and the evidence linking documentation to the improvement in the systems evolution, their practical adoption seems to be sparse. To understand this issue, we have conducted an overview of state-of-the-art on documentation of design decisions. We pursue an identification of characteristics of the different techniques proposed in the literature, such as the final goal of the documentation, the quantity of information attached to each decision documentation, the rigour of the proposed technique or its level of automation. To unveil these, we propose six classification dimensions, relevant for the industrial application, and use them to structure and analyse the review results. This work contributes with a taxonomy of the area, a structured overview covering 96 publications and a summary of open questions, which can be addressed by future research to facilitate practical adoption.