Document JMH data model

[hendrikebbers]

When executing JMH by code the result is defined as a collection of org.openjdk.jmh.results.RunResult. We should add a documentation of that model and all parts to define what information we want to extract.

I assume 2 types of documentation will make sense:

• provide the javadoc of the jmh code at a open elements server (see Define a way to deploy & run services #7)
• create a markdown based documentation (with draw.io based diagrams) of the data model.