Merge pull request #1761 from webbhuset/added-missing-upgrade-doc

Added missing upgrade doc for (,)

Author: evancz

upgrade-docs/0.19.md

@@ -58,6 +58,7 @@ Both are quite similar to the `elm-package.json` format, and `elm-upgrade` can h
 - `Basics.toString` becomes [`Debug.toString`](https://package.elm-lang.org/packages/elm/core/latest/Debug#toString), [`String.fromInt`](https://package.elm-lang.org/packages/elm/core/latest/String#fromInt), and [`String.fromFloat`](https://package.elm-lang.org/packages/elm/core/latest/String#fromFloat).
 - `Basics.rem 451 10` becomes [`remainderBy 10 451`](https://package.elm-lang.org/packages/elm/core/latest/Basics#remainderBy)
 - `451 % 10` becomes [`modBy 10 451`](https://package.elm-lang.org/packages/elm/core/latest/Basics#modBy)
+- `(,)` becomes [`Tuple.pair`](https://package.elm-lang.org/packages/elm/core/latest/Tuple#pair)
 - `style : List (String, String) -> Attribute msg` becomes `String -> String -> Attribute msg`
 - `Html.beginnerProgram` becomes [`Browser.sandbox`](https://package.elm-lang.org/packages/elm/browser/latest/Browser#sandbox).
 - `Html.program` becomes [`Browser.element`](https://package.elm-lang.org/packages/elm/browser/latest/Browser#element) and [`Browser.document`](https://package.elm-lang.org/packages/elm/browser/latest/Browser#document).