Too Long; Didn't Read
A simple rule to write important stuff is to write it down somewhere that we can use it later. It's important to document decisions, how do things work, etc. It's salient to understand why a decision was made and why we did something in X way. Documentation is a good way to keep track of a project's progress, but it's also important to update the docs. Documenting a product is a way of keeping track of your best practices, and if you have suggestions for better - please share.