A useful decision record does not need to be long. It needs to preserve the context, the options that were considered, and the reason one direction won.
Write the note close to the moment of the decision, then link it from the project where people will naturally look for it. A stable address and a clear date are often more valuable than a perfect format.
For a simple starting point, see the Architecture Decision Records guide. Replace this example with a source that supports your own thought.