Update readme

README.md

@@ -97,6 +97,7 @@ config.direct_otp_length = 6  # Direct OTP code length
 config.remember_otp_session_for_seconds = 30.days  # Time before browser has to perform 2fA again. Default is 0.
 config.otp_secret_encryption_key = ENV['OTP_SECRET_ENCRYPTION_KEY']
 config.second_factor_resource_id = 'id' # Field or method name used to set value for 2fA remember cookie
+config.delete_cookie_on_logout = false # Delete cookie when user signs out, to force 2fA again on login
 ```
 The `otp_secret_encryption_key` must be a random key that is not stored in the
 DB, and is not checked in to your repo. It is recommended to store it in an