Salesforce example case - needs to have "account" specified

[tplevko]

In the document readme.didact.md, there should be explicitly mentioned, that when creating the sample case on salesforce, the case should have the "account" field specified.

Otherwise the integration results in:

org.apache.camel.language.bean.RuntimeBeanExpressionException: Failed to invoke method: [Account][Name] on java.util.LinkedHashMap due last method returned null and therefore cannot continue to invoke method [Name] on a null instance