Access to multi-tenant app (#18080)

* Access to multi-tenant app doc

sdk/spring/azure-spring-boot-starter-active-directory/ACCESS_TO_MULTI_TENANT_APP.md

@@ -0,0 +1,25 @@
+# Access to multi-tenant app
+
+* Do not configure **tenantId** in the **application.properties/.yml** of a multi-tenant app or configure it to "common" to use the login process of multi-tenant access. Otherwise, users of other tenants will not be able to access the protected resources of the app.
+
+* The administrator's consent is required for the first visit.
+
+![need-admin-approval](resource/access-to-multi-tenant-app/need-admin-approval.png)
+
+* Sign in with an administrator account and approve.
+* Before accepting, make sure that **"Consent on behalf of your organization"** is checked.
+
+![permissions-requested](resource/access-to-multi-tenant-app/permissions-requested.png)
+
+* If you forget to check "Consent on behalf of your organization", there are two ways to revoke your consent.
+
+* Users revoke access to individual applications by removing them from their [Access Panel Applications list](https://myapps.microsoft.com/).
+
+![users-revoke-access-1](resource/access-to-multi-tenant-app/users-revoke-access-1.png)
+![users-revoke-access-2](resource/access-to-multi-tenant-app/users-revoke-access-2.png)
+![users-revoke-access-3](resource/access-to-multi-tenant-app/users-revoke-access-3.png)
+
+* Administrators revoke access to applications by removing them using the Enterprise applications section of the [Azure portal](https://portal.azure.com/).
+
+![administrators-revoke-access-1](resource/access-to-multi-tenant-app/administrators-revoke-access-1.png)
+![administrators-revoke-access-2](resource/access-to-multi-tenant-app/administrators-revoke-access-2.png)