I don’t know for sure, since I bought FCP 5.0 and then bought the 5.1 upgrade.
But, knowing the cost of re-editing the manuals and reprinting every time an upgrade is released is prohibitive, then I believe that you will get the set of 5.0 manuals and a drop-in upgrade package of disks and possibly even a thin booklet of update notes.
This is not really going to matter, since you say you are just starting, and many of the notes tell of how something that was supposed to have worked, now indeed work correctly. Here is a link to the changes made since 5.0: manuals.info.apple.com/en/Final_Cut_Pro_5.0_lbn_z.pdf. Browse it once, and it it makes no sense to you yet then that is good. If you need anything in the updates for your particular setup or workflow, then read that bit more carefully. Once you install FCP 5.1.2, you have at your fingertips the entire manual, as a searchable pdf (but apparently not the 5.1+ updates). My manuals are still in their box, since it is usually faster to search in the pdf file available through the FCP Help menu. Buy the FCP 5 Peachpit Apple Pro Training series book and do all of the tutorials, since it is the training material used in the instructor-led Apple approved training. The supplied manuals are reference/background materials, and for most people are a hard slog.
Bottom line, save your money. Get the cheaper package for less, then do the cross-grade for US$99 (before Dec 20).
Bill Lee