Update Readme (#107)

Tiny follow up to #105

README.md

@@ -18,7 +18,7 @@ Starting from Julia 1.0, the `Missing` type and basic related functionality are
 For documentation see [the Julia manual section on missing values](https://docs.julialang.org/en/v1/manual/missing/index.html).
 
 This package provides additional functionality for working with `missing` values:
-- `Missings.nonmissingtype` to extract `T` from a `Union{T, Missing}` type
+- `nonmissingtype` to extract `T` from a `Union{T, Missing}` type
 - `allowmissing` and `disallowmissing` to convert between `Vector{T}` and `Vector{Union{T, Missing}}`
 - `passmissing` to wrap a function so that it returns `missing` if any of its positional arguments is `missing`
 - `levels` to get the unique values in a vector excluding `missing` and in their preferred order