Update identity-model.md

Updated some spacing and made correction in case sensitivity

Author: FarrukhGhaffar

articles/communication-services/concepts/identity-model.md

@@ -20,7 +20,7 @@ Azure Communication Services is an identity-agnostic service, which offers multi
 - Provides integration flexibility as identity-agnostic model works well with your existing identity system.
 - You can Keep your user's data, such as their name, private as you don't need to duplicate it in Azure Communication Services.
 
-Azure communication service identity model works with two key concepts.
+Azure Communication Services identity model works with two key concepts.
 
 ## User Identity / Mapping:
 Uniquely identifies a user through a user-identifier, which is generated by Azure Communication Services when a user is created. External identifiers such as phone numbers, users, devices, applications, and GUIDs can't be used for identity in Azure Communication Services. You can create Azure Communication Service user identities for free. Charges are only incurred when the user consumes communications modalities such as a chat or a call. Your users identity can be mapped to Azure Communication Services user Identity in 1:1, 1:N, N:1, N:N configurations. A user can participate in multiple communication sessions, using multiple devices, simultaneously. Mapping between Azure Communication Services user identity and customer's private user identity is kept and maintained by the customer. For example, customers can add a `CommunicationServicesId` column in their user table to store the associated Azure Communication Services identity.