[pydotorg-www] Resource book lists are mostly one publishing house

[Frances Hocutt]

Hello all,

While going through the wiki working on Python 3 updates, I noticed
that these two pages now stretch to hundreds of books from a single
publisher:

 https://wiki.python.org/moin/IntroductoryBooks
 https://wiki.python.org/moin/AdvancedBooks

This seems like it runs into spamming/broad self-promotion more than a
usefully curated list of resources, but I'm not familiar with how this
wiki usually handles that kind of thing. Could someone more familiar
with this wiki take a look?

Thank you,
Frances