Clarification of SVM Usage in Example

The examples pass a `coarse_svm_vector` to a kernel functor without explicitly calling `unmap`, isn't that undefined behavior since the allocator maps on creation?

Start with the examples that pass `coarse_svm_vector` to a kernel functor and trace how the allocator maps it on creation. Check the OpenCL-CLHPP usage and relevant OpenCL SVM semantics; the issue is done when the required `unmap` behavior is confirmed and the example or its documentation clearly explains it.

Written by the indexing model from the issue text.