Typo in is_numeric() documentation

[jedwards24]

New line required in is_numeric() documentation https://github.com/tidyverse/purrr/blob/5aca9df41452f272fcef792dbc6d584be8be7167/R/predicates.R#L3-L8

The text starting "This function tests..." is rendered as part of the third bullet.

Suggest change to:

#' Numeric is used in three different ways in base R:
#' * as an alias for double (as in [as.numeric()])
#' * to mean either integer or double (as in [mode()])
#' * for something representable as numeric (as in [as.numeric()])
#'
#' This function tests for the second, which is often not what you want
#' so these functions are deprecated.