business operations handbook update

Why is this change being made?

• removed planning hat section
• removed section on metrics (404 error)
• moved the issues under the departments
• updated the BSA page with links to boards
• minor formatting
• changed some words from tool to application
• added a sentence about architecting the data flow and processes relating to the enterprise application ecosystem
• updated bsa page title to business engagement team

cc @bryanwise @gitlab-com/business-ops/bizops-bsa

Does this MR meet the acceptance criteria?

Conformity

• Added description to this MR explaining the reasons for the proposed change, per say-why-not-just-what