Your driver's license is documentation of your age, address, and that you have passed the tests required to drive a car. Documentation is certifiable proof, or a set of official documents.
Your new computer probably came with a packet of documentation that shows you how to use it and explains what to do when it breaks. In this sense, documentation means the official documents of your computer. If you are the person preparing a packet of information about how to use a computer program to keep attendance at school, you are preparing the documentation of that process.