In the range_keys "bad example", the real problem is that using a set to group all of a user's orders breaks once the user item reaches the 64KB limit -- you can no longer add orders.
"lastUpdate": lambda: datetime.now() -- use "last_update" (consistency between key names), and the lambda can be simplified to simply datetime.now. However, datetime.now creates timezoneless datetime objects by default, so lambda: datetime.now(tz=utc_tz) is even better.
Please replace the French comments/notes with equivalent English ones.
When discussing strong VS eventual consistency: eventual consistency is the only available mode for scan, not query (query and get support strong consistency, scan and get_batch don't).
In the "get Chuck Norris" example, there are stray references to data.h_key (should be replaced with my_user.fullname).
In the "get last blog post" example, there's a bare except: block. You should never use those (they will even catch SystemExit and KeyboardInterrupt). Explicitly expect StopIteration, or even better, run list() on the generator to get an actual list.
The BundleTransaction example defines BundleTransaction.init, which doesn't call Transaction.init (or better, super(BundleTransaction, self).init).
More to follow, AFK daily scrum ;) . Great work so far, aside from that.
In the create_table example/doc, it might be a good idea to mention that a table isn't usable as long as it's in the CREATING state, and that table creation can take more than a minute (it's a very surprisingly long time IMO -- compared to Mongo that does it so fast it can even do it on the fly).
The _save_autoincrement_hash_key method should probably mention that the magic item is stored at MAGIC_KEY rather than at 0 (besides, it's -1 now, isn't it?).