Added answers for Azure IaaS, PaaS, SaaS, Azure Virtual Network, and …

[GMATHUR90]

…Azure AD

This commit includes detailed answers for the following Azure-related questions:

Q4: Describes the differences between Azure's Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (SaaS), covering their key characteristics and use cases. Q5: Explains how Azure Virtual Network (VNet) works, outlining its components like subnets, network security groups (NSGs), VPN gateways, and peering configurations that enable secure network communication. Q6: Provides an overview of Azure Active Directory (Azure AD), its features, and its common use cases in identity and access management across cloud resources.

Please review the newly added answers for questions related to Azure services. The content has been structured to provide valuable insights for anyone learning about Azure’s infrastructure, platform, and directory services. I’d appreciate your feedback, and if everything looks good, kindly approve the pull request to integrate these answers. Thank you!