Update User Guide with new features and teminology

[Oleksandr123234]

This task involves a detailed review and update of the KubeRocketCI user guide. The primary focus is to replace all mentions of 'Environments' with 'Deployment Flows' to reflect the latest terminology and conceptual framework adopted by the KubeRocketCI platform. The goal is to ensure the user guide accurately represents the current capabilities, workflow, and terminologies used in the KubeRocketCI platform, providing clear and updated guidance to users.