Update step-1-hello-world-typescript-c20489e.md

[stefango79]

Missing comma in manifest.json

Error Message:
Failed to read /manifest.json for project ui5.walkthrough: Expected ',' or '}' after property
value in JSON at position 79 (line 4 column 32)

[cla-assistant]

All committers have signed the CLA.

[cla-assistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[KvM2]

Hi @stefango79, thanks for your contribution! We'll look into it and get back to you.

[KlattG]

Duplicate of #156