Document aggregate.py and parse_results.py scripts

[melhindi]

The src/macro/kvstore folder contains two python script that look like they should help in parsing and aggregating the benchmark result from multiple clients. However, the script are hardly documented and also look for a "Throughput" string (line 31 in aggregate.py) in the log which is not printed by the driver.

Which logs are supposed to be processed with the scripts?

[ug93tad]

this is the relics from the original YCSB code https://github.com/basicthinker/YCSB-C

we don't use them, and will remove them.