Improve some learning-basics code samples

[olukas]

Following code samples in learning-basics should be improved to be more readable and understandable:

• destroying-instances - I suggest to rename this code sample to destroying-distributed-object
• unique-names - there is missing some description about what is the point of this code samples. Even if code includes just a 3 lines it is quite confusing. Some explanation would be useful.
• wildcard-configuration - there is missing some description about what is the point of this code samples. There should be probably mentioned that wildcard is used in xml configuration.