doc: Update documentation for Resources view for execution context

doc: Update documentation for Resources view for execution context

Now the Resources view show IRQs under CPUs and CPUs under IRQs.

https://git.eclipse.org/r/#/c/65609/

Change-Id: I36fe7156e66fdb6dec2c580be024c27a1c67ba74
Signed-off-by: Marc-Andre Laperle <marc-andre.laperle@ericsson.com>
Reviewed-on: https://git.eclipse.org/r/72581
Reviewed-by: Hudson CI
Reviewed-by: Bernd Hufmann <bernd.hufmann@ericsson.com>
Tested-by: Bernd Hufmann <bernd.hufmann@ericsson.com>