make example dataset more realistic

[adw96]

Hi Brian! It looks to me like full_data doesn't much mimic the structure of absolute and relative abundance datasets that we typically see.

Could you add a significant amount of noise to a dataset that you have already looked at and distribute that as a pre-loaded dataset example_data? (A list with two elements: relative and absolute)

I would love for the most basic vignette/example to be as easy as

data(example_data)
run_paramedic(example_data)

i.e., not have the homepage involve generating fake data and processing it before running it. (I'm always suspicious of packages whose example data is simulated on-the-fly -- it suggests that they don't actually care about analyzing users' data)

[adw96]

This issue also affects the vignette and the README

[bdwilliamson]

Done in all three places! Good call on making the pipeline simpler, and including a more realistic dataset.