I like this and explains the basic mechanics in a simple way for me to understand.

I want to highlight the What counts as revenue section because I think it is the most crucial. Deferred Revenue is well explained and very necessary for SaaS. I think it will also be good to highlight account receivables, where you have delivered the good but haven't received the cash. Even though this rarely occurs in a SaaS model, but it is important to state that account receivable is not revenue, which some awkward mistake can be easily made.