Add documentation for blocking data sharing use case on Segment

[mfbrown]

As a web developer, I want to use the status of the data sharing flag in the eth_cmp cookie to block additional destinations in segment.

Details

It looks like we’re currently blocking only activities in Segment where the category is defined as “Advertising”

AC

Update the Segment documentation to reflect the changes required to support blocking the data sharing use case.

The ethyca-segment.js snippet is updated to incorporate group5 from the eth_cmp cookie, so that it can be exposed to the Segment tracker.