Consider adding interactive notebooks as examples

[kennknowles]

For an example see:
https://github.com/quantopian/zipline/blob/master/zipline/examples/buyapple.ipynb

These notebook, hosted on github might be a nice interactive basic examples for first time users.

cc: [~tibor.kiss@gmail.com]

Imported from Jira BEAM-2104. Original Jira may contain additional context.
Reported by: altay.