adds collaborative filtering notebook example

[justin-cechmanek]

No description provided.

[tylerhutcherson]

Nice work! My feedback below, just a few things!!

• Link back to content filtering notebook/recipe up top to help people who may be new or are getting started go through the easier example first?
• The explanation of the range query score output as it relates to rating predictions could be clearer (should we have a helper method to convert this value?)
• Consider storing the user items in a separate index to handle two things -- storage of users/metadata/vectors in a more production like way. Retriever user from DB and then do the inference? Just an idea.
• Love the bloom filter approach, but I think we need to lay the baseline with just standard title/ID based filtering using a TAG filter first. And then build to why a bloom filter works here and what problem it solves.

[rbs333]

This is a really awesome recipe! Tyler's comments are good and I would also say to add a link to this in the root level readme.