fix date

Author: hpsin

articles/active-directory/fundamentals/whats-new.md

@@ -211,7 +211,7 @@ For more information, see [How to enable password reset from Windows 7, 8, and 8
 **Service category:** Authentications (Logins)  
 **Product capability:** User Authentication
 
-Starting on October 10, 2018, Azure AD will stop accepting previously used authentication codes for apps. This security change helps to bring Azure AD in line with the OAuth specification and will be enforced on both the v1 and v2 endpoints.
+Starting on November 15, 2018, Azure AD will stop accepting previously used authentication codes for apps. This security change helps to bring Azure AD in line with the OAuth specification and will be enforced on both the v1 and v2 endpoints.
 
 If your app reuses authorization codes to get tokens for multiple resources, we recommend that you use the code to get a refresh token, and then use that refresh token to acquire additional tokens for other resources. Authorization codes can only be used once, but refresh tokens can be used multiple times across multiple resources. An app that attempts to reuse an authentication code during the OAuth code flow will get an invalid_grant error.
 
@@ -295,7 +295,7 @@ We strongly recommend not removing the old IP Address ranges until all of your n
 **Service category:** Authentications (Logins)  
 **Product capability:** User Authentication
 
-Starting on October 10, 2018, Azure AD will stop accepting previously used authentication codes for apps. This security change helps to bring Azure AD in line with the OAuth specification and will be enforced on both the v1 and v2 endpoints.
+Starting on November 15, 2018, Azure AD will stop accepting previously used authentication codes for apps. This security change helps to bring Azure AD in line with the OAuth specification and will be enforced on both the v1 and v2 endpoints.
 
 If your app reuses authorization codes to get tokens for multiple resources, we recommend that you use the code to get a refresh token, and then use that refresh token to acquire additional tokens for other resources. Authorization codes can only be used once, but refresh tokens can be used multiple times across multiple resources. An app that attempts to reuse an authentication code during the OAuth code flow will get an invalid_grant error.