Make account type not optional

Recently was trying to this with a single tenant account type and got hung up on this for a while until I changed the the account type to the skype one. So I'm not sure how optional this actually is.

docs/prerequisites.md

@@ -10,7 +10,7 @@ To allow authentication, you first need to register your application at Azure Ap
 
 1. Login at [Azure Portal (App Registrations)](https://portal.azure.com/#blade/Microsoft_AAD_RegisteredApps/ApplicationsListBlade). Personal accounts may receive an authentication notification that can be ignored.
 
-2. Create a new App Registration. Give it a name. In Supported account types, choose "Accounts in any organizational directory and personal Microsoft accounts (e.g. Skype, Xbox, Outlook.com)" for greatest freedom of login account. Choose other options if you are confident it will cover the type of account you are using to login.  Click Register.
+2. Create a new App Registration. Give it a name. In Supported account types, make sure you choose "Accounts in any organizational directory and personal Microsoft accounts (e.g. Skype, Xbox, Outlook.com)"
 
 3. Click Add a Redirect URI. Click Add a platform. Select Web. Set redirect URI to: `https://login.microsoftonline.com/common/oauth2/nativeclient`, leave the other fields blank and click Configure.