Update nodejs-beginners-tutorial.md to fix error

[justinzw]

I ran through the tutorial. The issue with using echo var msg > app.js is that by default it created a UTF-16 format file which then created extra characters and node did not like.

I changed the tutorial around so that you create the file "app.js" inside of VS code instead of echo to create it.

By default this will create the file in the right format.

[prmerger-automator]

@justinzw : Thanks for your contribution! The author(s) have been notified to review your proposed change.

[learn-build-service-prod]

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