Signpost to additional samples

I think we should add signposting to other curated samples that aren't necessarily ported to the SDK repo yet or perhaps never will be. As an example, the University of Bristol's "Hands on OpenCL" samples are excellent:

* https://github.com/HandsOnOpenCL/Exercises-Solutions

We could do this directly from the README or from a companion page.

Start by reviewing the repository README and considering whether a companion page is more appropriate. Add a signpost to the Hands on OpenCL Exercises-Solutions samples, with the link provided in the issue; done means readers can discover these additional curated samples.

Written by the indexing model from the issue text.