README Link pointing to removed file

[jukkakarvanen]

In #219 WordCountLambdaIntegrationTest.java was replaced by WordCountLambdaExampleTest.java.

Merging of #219 and README improvements has caused test Table is pointing to non existing file

I also change header title from "Integration Test Name" -> "Test Name"

I am not sure should what these Concepts used now in this test table should refer.
Concept used in Test class or actual implementation class?

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