Check that all exported functions have `@return` and `@examples`

[TNRiley]

[TNRiley]

@DrMattG @kaitlynhair @LukasWallrich - I've been working on the @examples and have made a lot of progress, but am still not 100% on @examples - specifically, which functions are required to have them (plots/tables?) Just looking for a little assistance or a review of what I've added thus far. Thanks :)

[DrMattG]

Added example to tables.R - I think these are useful as interactive examples (but happy whatever way!). I think it is useful to have example code for all external (exported) functions

[TNRiley]

@DrMattG will add the data - check the plots examples @TNRiley - technically ok, but want to use real data

[TNRiley]

@TNRiley remove if interactive from any functions that need to be displayed, keep for reading/writing functions

[TNRiley]

Will need to wait for #86 to be completed

[TNRiley]

complete with 0.2.0