Added content and outline for on-prem v2.1

Added initial set of bug fixes

update pipeline scopes and added initial draft of cron trigger desc

Added more bug fixes

Added docker registry and phone number to bug fixes

Added desc for account ID in URL

Added more bug fixes

Added list of FFs

Added missing FF descriptions, links to doc articles, and new screenshots for features

Minor edits for session cookie description

Updated bug fix desc for concurrent sessions and added desc for accessibility contrast

Added description for OpenShift

Added new FRAME_OPTIONS env variable description

Fixed path for pipeline status icons and added Gerrit FFs to table

Added blurb for OIDC in pipelines

Added OIDC feature flag; added new bugs closed in S6 - commented out until confirmation

Minor edit

Removed max pipelines in project config variable option from 2.1 release notes

Restored desc on pipeline limit env variable and gitops session cookie variable

Added desc for new helm install and more bug fixes

Added section for v2.1 install/upgrade, and one for Runner Helm installation

Added next gen terminal to FFs

Added desc for next gen terminal