minor #8856 Separate dev dependencies from application dependencies (Tucker-Eric)

This PR was merged into the 4.0 branch.

Discussion
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Separate dev dependencies from application dependencies

react react-dom and prop-types shouldn't be dev dependencies

Commits
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d1f32b3 Separate dev dependencies from application dependencies

Author: javiereguiluz

frontend/encore/reactjs.rst

@@ -5,7 +5,8 @@ Using React? Make sure you have React installed, along with the `babel-preset-re
 
 .. code-block:: terminal
 
-    $ yarn add --dev react react-dom prop-types babel-preset-react
+    $ yarn add --dev babel-preset-react
+    $ yarn add react react-dom prop-types
 
 Enable react in your ``webpack.config.js``: