Add a guide to the playbook on decision making and documenting rationale

[kellylee-gds]

What

Add a guide to decision making. It should include techniques to use, and how decisions should be recorded.

Why

Many of the team have expressed it's challenging to make decisions or approach others to instigate a decision.

Who needs to work on this

A delivery manager

Who needs to review this

Anyone

Done when

• [x] draft completed
• [ ] draft reviewed
• [ ] published on playbook