Add react-script npm install to read-me

[thohenadl]

In case of error
'react-scripts' is not recognized as an internal or external command, operable program or batch file. error Command failed with exit code 1.

install the following library

npm install react-scripts

Source for solution: https://stackoverflow.com/questions/48942639/react-scripts-is-not-recognized-as-an-internal-or-external-command-operable-p

[thohenadl]

And if
yarn start

fails with

https://stackoverflow.com/questions/69692842/error-message-error0308010cdigital-envelope-routinesunsupported

Edit in package.json:
"start": "react-scripts start ",
to
"start": "react-scripts start --openssl-legacy-provider start",

Solution from: https://stackoverflow.com/questions/69692842/error-message-error0308010cdigital-envelope-routinesunsupported