Unify test directory structure with other examples

Author: k-stachowiak

tests/README.md

@@ -0,0 +1,11 @@
+# Testing examples
+
+Examples are tested using tool [htrun](https://github.com/ARMmbed/mbed-os-tools/tree/master/packages/mbed-host-tests) and templated print log.
+
+To run the test, use following command after you build the example:
+```
+mbedhtrun -d D: -p COM4 -m K64F -f .\BUILD\K64F\GCC_ARM\mbed-os-example-atecc608a.bin --compare-log tests\atecc608a.log
+```
+
+
+More details about `htrun` are [here](https://github.com/ARMmbed/htrun#testing-mbed-os-examples).