Relabel a subset of the variables.
Examples
x <- var_relabel(iris, Sepal.Length = "Sepal Length of iris flower")
var_labels(x)
#>                  Sepal.Length                   Sepal.Width 
#> "Sepal Length of iris flower"                            NA 
#>                  Petal.Length                   Petal.Width 
#>                            NA                            NA 
#>                       Species 
#>                            NA