Simplifying documentation and shared responsibility documentation

[choldgraf]

This refactors and simplifies our service documentation with a few major goals:

• Reduce the total number of pages that users click through
• Make our Shared Responsibility Model more well-described
• Move some of the strategic and policy documentation to our Team Compass (because even I had forgotten it was in here)
• Reduce duplicated and redundant information and instead link to a single source of truth

Still WIP but posting here as a first step in case there is feedback.

To Do

• [ ] Flesh out the Shared Responsibility Model section

References

• ref: https://github.com/2i2c-org/docs/issues/173
• sibling to: https://github.com/2i2c-org/team-compass/pull/572

[yuvipanda]

This has been open long enough, let's merge this. Thanks @choldgraf