small font change

README.md

@@ -126,7 +126,7 @@ the SSH key-pair used by the login credentials you want to use for
 accessing the Debian repository server. Note that this value is a _secret_
 so be sure that the only people how have access to maintain your
 repository have permission to see this value.
-*Warning.* Be sure that the string containing the private key you set in the
+**Warning.** Be sure that the string containing the private key you set in the
 CI/CD File variable has a _trailing new-line_. If not then OpenSSH will
 not be able to parse it and return an invalid format error.