docs: define security hierarchy and RBAC roles

Signed-off-by: SyedAsad108 <ID+username@users.noreply.github.com>

Author: SyedAsad108

content/en/cloud/security/_index.md

@@ -1,10 +1,49 @@
 ---
 title: Security
-description: Tokens, Keychains, Keys, Roles
+description: Manage identity and access through Tokens, Keychains, Keys, and RBAC Roles.
 weight: 4
 categories: [Security]
-tags: [permissions]
+tags: [permissions, identity, authentication]
 ---
 
+Layer5 Cloud provides a multi-tenant security model designed to manage access across complex organizational structures. This section covers the core components of our Identity and Access Management (IAM) system.
 
-![permission](/cloud/security/images/permissions.svg "image-center-shadow")
+## Security Architecture
+
+The following diagram illustrates the relationship between Organizational Units, Roles, and the underlying Permissions:
+
+![permission](/cloud/security/images/permissions.svg "image-center-shadow")
+
+---
+
+## Organizational Units
+Layer5 Cloud uses a hierarchical structure to isolate resources and manage users at scale:
+* **Provider Organizations:** The top-level entity that can manage multiple tenant organizations.
+* **Tenant Organizations:** Individual customer or project-specific organizations (e.g., Layer5, Intel).
+* **Teams:** Logical groupings of users within an organization to facilitate collaborative management.
+* **Users:** Individual accounts that are members of teams and organizations.
+
+## Roles and Access Control
+Access is granted through Role-Based Access Control (RBAC). Roles are assigned at different levels of the organizational hierarchy:
+* **Organization Administrators:** Full control over an entire tenant organization.
+* **Organization Billing Managers:** Access restricted to subscription and financial management.
+* **Team Administrators:** Management of specific team resources and memberships.
+
+## Key Management and Tokens
+Beyond structural roles, Layer5 Cloud uses cryptographic and session-based security:
+
+### Keychains
+Keychains are collections of keys used to manage environment-specific access and signing. They allow for the logical grouping of related security credentials.
+
+### Keys
+Keys are the atomic unit of access control within the system. They are used for secure communication between Meshery and Layer5 Cloud, as well as for signing design patterns.
+
+### Tokens
+Tokens provide temporary, secure access to the platform.
+* **Session Tokens:** Used for web browser authentication.
+* **Personal Access Tokens (PATs):** Used for programmatic access via CLI or CI/CD pipelines.
+
+---
+
+### Need more detail?
+Check out the [Roles Reference](/docs/security/roles) for a complete matrix of permissions for each role.