doc/index: Update intro description of WA.
doc/index: Update intro description of WA.

setrofim/workload-automation,ARM-software/workload-automation,lisatn/workload-automation,setrofim/workload-automation,ARM-software/workload-automation,ARM-software/workload-automation,ARM-software/workload-automation,setrofim/workload-automation,lisatn/workload-automation,lisatn/workload-automation,lisatn/workload-automation,setrofim/workload-automation