It's a great idea, but first you need to first determine who will be audience of your team handbook. Is it for new members, existing members, parents, etc, or all of the above? Then sit down and decide what you need to share with them. And also consider the size of the handbook, and how you will print and distribute it. If you have to make paper copies, the shorter the better. An electronic version is more versatile, but not as many people will take the time to read through the entire book. You should try and make most content evergreen, in order to minimize the amount of updating you will have to do next year.
Our team's handbook can be found at
http://moe365.org/teamdocs/handbook.pdf