Add reference docs for the load generator

[danielmitterdorfer]

We should add reference docs that describe relevant information about the load generator from a user perspective (this needs to be a new page in the docs). Two aspects are:

• [x] Create charts explaining the dynamics of target-throughput/interval / num of clients / bulk_size / iterations / schedule - owned by @dliappis
• [ ] move the scheduler docs from the track reference to the new page and add charts from ^^ item - owned by @hub-cap
• [ ] Provide a high-level introduction and specifically document how clients are assigned to OS processes and load generator hosts - owned by @hub-cap
• [ ] Measure and document how throughput / number of active clients as a function of the number of clients specified - owned by @ebadyano

[dliappis]

@hub-cap / @ebadyano I've edited this issue:

1. I've added a task (owned by me) to provide charts describing the interplay between bulk_size, num of clients and target-throughput/target-interval.

2. I moved the item to change the location of the scheduler docs to be after 1. The charts from 1. should be placed there. @hub-cap owns this.

@hub-cap Here are the charts I came up with (I can provide them in other formats too like svg, pdf, without background etc.):

Target-throughput with 2 clients

Target-interval with 1 client

Target-interval with 2 clients