Remove seed from examples

[sjspielman]

I would remove passing in a seed in the examples (all around I guess), but I would also not show set.seed() in the package code examples. That level of detail makes the most sense to me in the example notebooks, not in individual function docs.

Originally posted by @jashapiro in #23 (comment)

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This issue tracks updating examples in the roxygen comments to remove any seed setting or passing.