Further fine tuning the pre-requisites

Further fine tuned the pre-requisite sections and added a message prompt to reduce ambiguity.

Author: Muralidhar Ranganathan

articles/active-directory/authentication/howto-authentication-passwordless-security-key-on-premises.md

@@ -53,8 +53,8 @@ You must also meet the following system requirements:
     - [Windows Server 2016](https://support.microsoft.com/help/4534307/windows-10-update-kb4534307)
     - [Windows Server 2019](https://support.microsoft.com/help/4534321/windows-10-update-kb4534321)
 - Credentials required to complete this :
-    - Active Directory User who is a member of the "Domain Admins" group for a domain and a member "Enterprise Admins" group for a forest. Referred to as $domainCred.
-    - Azure Active Directory User who is a member of the Global Administrators role. Referred to as $cloudCred.
+    - Active Directory User who is a member of the "Domain Admins" group for a domain and a member member of the "Enterprise Admins" group for a forest. Referred to as **$domainCred**.
+    - Azure Active Directory User who is a member of the Global Administrators role. Referred to as **$cloudCred**.
 
 ### Supported scenarios
 
@@ -111,7 +111,7 @@ Run the following steps in each domain and forest in your organization that cont
    $domain = "contoso.corp.com"
 
    # Enter an Azure Active Directory global administrator username and password.
-   $cloudCred = Get-Credential -Message 'Active Directory User who is a member of the "Domain Admins" group for a domain and a member "Enterprise Admins" group for a forest.'
+   $cloudCred = Get-Credential -Message 'Active Directory User who is a member of the "Domain Admins" group for a domain and a member member of the "Enterprise Admins" group for a forest.'
 
    # Enter a domain administrator username and password.
    $domainCred = Get-Credential -Message 'Active Directory User who is a member of the "Domain Admins" group.'