Extended tutorial for baselines

[spirinamayya]

Description

Added extended tutorial for baselines Closes https://github.com/MobileTeleSystems/RecTools/issues/137

[feldlime]

Don't pay attention to the number of comments, I really like your notebook, it looks fabulous! I can't even imagine how much time it took to write such an extensive model descriptions and to draw such a nice pictures, and I really appreciate that. Thank you!

[blondered]

I must also emphasize, that we are still excepting (and will be excepting after merge) more links, explanations and practical advices from practitioners. And we really appreciate everyone to join us sharing their expertise and accumulating it in one place.

[feldlime]

Please add one of the keywords (I prefer Closes) before the issue link in the description