Hello Tom T.,
Welcome to the team! I'm a volunteer (at the moment, the only one, it seems) working on updating the Base Handbook. I'd like to supplement the information that Tom D. has provided you with and let you know how you might start out getting involved with the project.
As Tom indicated, the Base Guide and the Base Handbook are two different documents, which is confusing. Base is the only LO product for which this is the case; for all the other products, the user manual is just called the Guide. However, there is not now, nor has there ever been, a complete Base Guide; all there is is the drafts of three chapters.
The reason that there's both a Guide and a Handbook is that the German documentation team got tired of waiting around for the English team to finish the Base Guide, so they took the draft chapters, translated them, finished the book, and published it as the Base-Handbuch. That document was then translated back into English as the Base Handbook.
Contrary to what Tom D. indicated, the Handbook is /not/ shorter or less thorough than the Guide. Each is intended to be a complete and comprehensive user manual; the difference is that the Handbook is finished (although not up-to-date in English.) The current German version of the Handbook has 448 pages in 11 chapters; the plan for the Guide includes 10 chapters, of which only 3 are complete.
The current English Handbook is for version 3.5 of the product. The most recent German Handbuch is for version 4.2. What I'm doing right now is updating the English Handbook from the more up-to-date German version. Someone else has done the translating; I'm basically just cutting-and-pasting (although I am finding that I have to do a fair amount of translating and editing work as I run across things that don't make sense.)
Here's one task we need done right away. The screen captures in the German manual are, as one would respect, from the German version of the app, and are in German. We need someone to work through the procedures described in the Handbook using the English version of the product and capture the needed screenshots in English. Moreover, this needs to be done by someone who's running Base on Linux. For reasons I don't understand, screen captures don't always work correctly when done using Windows, and Windows is what I'm running.
If this is something you'd be willing to do, respond to this e-mail and I'll send you more details on how to get started.
Best,
Alan C.