Add explanation of log files to the wiki

[ksonbol]

In the results folder, I have the file Master-result.log and a log file for each slave (e.g., slave1-result.log). I believe these are the only places where I can find the results of the queries. However, I couldn't find any explanation in the Wiki or the BenchFoundry paper about how to read these log files, and use them to extract useful information like the staleness values. This is an example line from one of the slave files:

5;180;0;3;126;139;SUCCESSFUL;[[myfield], ]

It'd be great if you could explain what this line means, and include such an explanation in the wiki.
Thanks in advance.