Teach and peer reviews remarks

Author: dshevtsov

mftf/2.3/credentials.md

@@ -67,7 +67,7 @@ carriers_usps_password=Lmgxvrq89uPwECeV
 ....
 ```
 
-## Use credentials in test
+## Use credentials in a test
 
 <!--{% raw %}-->
 Access the data defined in the `.credentials` file using the [`fillField`][] action with the `userInput` attribute.
@@ -89,6 +89,9 @@ The MFTF dynamically retrieves, encrypts, and decrypts the sensitive data during
 Decrypted credentials do not appear in the console, error logs, or [test reports][].
 The decrypted values are only available in the `.credentials` file.
 
+{: .bs-callout .bs-callout-info }
+The MFTF tests delivered with Magento application do not use credentials and do not cover external services, because of sensitivity of the data.
+
 <!--{% endraw %}-->
 
 <!-- Link definitions -->