Provide benchmark read frequencies when different PolledBno055Registers are selected

[jonnew]

If a subset of PolledBno055Regsiters are selected, then the read rate increases. We should document the expected rates, given some computer specs somewhere. Options include

1. A short tutorial
2. The template used to create these sections.

[cjsha]

I just ran a couple preliminary tests to see what to expect.

All registers queried:

Quaternion, Calibration registers queried:

the difference is mostly in std. dev, not sure it makes a big difference for average bno055 sample rate.

[cjsha]

This zip includes some data, the workflow I would use in the tutorial, and the script I would use to generate the plots in the above screenshots:

polled-bno055-sample-rate-test.zip