I don't know how long they've been doing this - I've only just spotted it myself but for anyone else who hasn't, it's darned useful! At the bottom of a lot of page listings, there's now a link to the instructruction manual/sheet for the item - notably electrical stuff I think - where they've scanned this in and made it available as a PDF file.
I've often found the page listings either incomplete or in error, so this is really useful. Just thought I'd pass this on for anyone who hasn't noticed it!
David