Clarification should be added for Interaction Based testing

[anshbansal]

In the section "Declaring Interactions at Mock Creation Time" it is written that if a mock has a set of "base" interactions [...].

I think some explanation should be added about the meaning of "base" interactions here. An example, link to explanation here etc.

[anshbansal]

I read it again and found that another section "Mocking All Instances of a Type" can use an additional example for ssing it with GroovySpy. Not must but good to have.