Update the instructions to run Creator system tests on a real hardware

[abhijit-mahajani-imgtec]

https://github.com/abhijit-mahajani-imgtec/creator-system-test-framework/blob/master/doc/hardware/README.md is bit outdated.

Acceptance:
So it should mention which OpenWrt image to be downloaded (vanilla or creator along with the exact link to the downloads.creatordev.io)
1.Any packages to be installed explicitly on host machine/ Ci40.
2.specific branch for Contiki/clicker based app.
3. Configuration instructions to setup wpan on Ci40.
4. Configuration/flashing instructions for constrained devices.
5. Test instructions for running tests on Ci40.
6. Test instructions for running app on Clicker.
7. Expected result on Ci40/Clicker. Any logs/prints to be seen on the respective console or look for test results on console?