Update installation_and_configuration_guide.md

docs/installation_and_configuration_guide.md

@@ -610,7 +610,8 @@ In most cases, they do not need to be changed.
 
 ## Configuring two-step OAuth 2.0 authentication
 
-If users use gmail accounts, then to connect CRM to them via SMTP and IMAP protocols, you will need to set up access and pass two-step authentication once.  
+In some cases, to access your Gmail account from CRM, you will need to set up access for third-party applications and go through two-factor authentication once.  
+The procedure is not simple. Therefore, first make sure that without passing it, the SRM really will not have access to your account.  
 Google APIs use the [OAuth 2.0 protocol](https://tools.ietf.org/html/rfc6749) for authentication and authorization.
 Visit the [Google API Console](https://console.developers.google.com/). Create "OAuth 2.0 Client IDs" settings
  for "Web application" to specify the Authorized redirect URI in the format:  
@@ -622,7 +623,9 @@ And also get the credentials OAuth 2.0 "CLIENT_ID" and "CLIENT_SECRET". Save the
 Then on the desired "Email Account" page  
  `(ADMIN) Home > Mass mail > Email Accounts`  
 In the upper right corner, click the button "Get or update a refresh token".  
-CRM will open the authorization page. After successful authorization, the "Refresh token" value will be received and CRM will get access to this account.
+CRM will open the authorization page. After successful authorization, the "Refresh token" value will be received and CRM will get access to this account.  
+Please note that in order to receive a refresh token, the CRM must be running on a server that supports the HTTPS scheme.  
+The refresh token can also be obtained separately from the CRM, for example using curl.
 
 ## Company product categories