This pull request introduces a new "Administration" section to the documentation, with a comprehensive guide to user roles and permissions in Kosli.

It clarifies the distinctions between Admin, Member, and Reader roles, provides a detailed permissions matrix, and maps organizational responsibilities to appropriate Kosli roles. These changes improve clarity for both administrators and end users, and update related implementation guides to reference the new roles documentation.

New Administration Section and User Roles Documentation:

• Added a new Administration section (_index.md) and a Managing users subsection to the documentation, establishing a clear structure for administrative topics. [1] [2]
• Introduced a detailed Roles in Kosli guide, including a permissions matrix, role descriptions, assignment guidance, best practices, and organizational role mapping. This helps users understand the capabilities and responsibilities associated with each role.

Updates to Implementation Guide and Role Mapping:

• Added explanations connecting organizational responsibilities (RACI model) to Kosli user roles, and referenced the new roles guide for further information.
• Updated implementation guide subpages for platform engineers, application developers, security/compliance, and sponsors to specify recommended Kosli user roles and link to the new roles documentation. [1] [2] [3] [4]

closes kosli-dev/customer-success#63