Create Azure article for identity management

Added an article on Azure identity management with details on app registration and service principals.

Author: monodot

_articles/azure.md

@@ -0,0 +1,11 @@
+---
+layout: page
+title: Azure
+---
+
+## Identity management
+
+In Microsoft Entra (formerly Active Directory):
+
+- **App registration** defines an application (client secrets, API permissions, redirect URIs, etc.). It is _"a template or blueprint to create one or more service principal objects."_
+- **Service principal** (also called **Enterprise Application** in the UI) is like an instance of the application. It defines the access policy and permissions for the user/application in the Microsoft Entra tenant. There can be many service principals linked to 1 app registration.