Re-factor documentation into Sauna-style personas

[alexanderdean]

As an example, this page is very confusing:

https://github.com/snowplow/iglu/wiki/Setting-up-Iglu#step2

A devops person would setup an Iglu schema registry; a developer (e.g. a Snowplow engineer) would integrate an Iglu client. They are very different roles.

[ndey96]

+1

It should be explained that most people using snowplow won't need to setup an iglu-client as it is baked into the snowplow enrichment stage.

https://github.com/snowplow/snowplow/wiki/Configurable-enrichments?_sp=02ee6a6e-820a-45a2-bf9b-8ad5b788d051.1484080225082