miss_guide_label: Label the legend with the percent of missing data
Description
miss_guide_label is an internal function for vis_miss to label the legend.
Usage
miss_guide_label(x)
Value
a tibble with two columns p_miss_lab and p_pres_lab,
containing the labels to use for present and missing. A dataframe is
returned because I think it is a good style habit compared to a list.