Update Slack branding from 'Slack App Directory' to 'Slack Marketplace'#1

codegen-sh[bot] wants to merge 1 commit intomaincodegen-sh/outline:mainfrom

codegen-cg-18226-f3-ensure-compliance-with-slacks-brand-guidelinescodegen-sh/outline:codegen-cg-18226-f3-ensure-compliance-with-slacks-brand-guidelinesCopy head branch name to clipboard