Add funnel metrics example & hub contribution

[skrawcz]

Is your feature request related to a problem? Please describe.
Businesses should be interested in the basics of customer metrics: DAUs, conversion of new users, retention.

But they end up having to write a lot of this logic themselves, or off load to some CDP. Wouldn't it be cool if we had examples and off the shelf code for people to just use!

Describe the solution you'd like
Example data source: zendesk (or some other application/tracking)
Show code to:

1. pull data and transform into a common schema.
2. then compute DAU, MAU, Conversion, Retention metrics.

Describe alternatives you've considered
N/A

Additional context
This could be a great addition to the hub and show how people can share/contribute code back for the community to use.