Verify Sales KPIs and definitions in handbook and create definition for those that are missing

link to sales KPIs: https://about.gitlab.com/handbook/business-ops/data-team/metrics/#sales-kpis

Verify that we have the correct Sales KPIs in the handbook, ensure the priority set by finance is correct for each KPI, add definition (and links) where missing, work with finance to ensure we have monthly goals for each KPI