docs: update minor for json-schema

[mavogel]

Issue #, if available:

• none available

Description of changes:
Fixed the listing of tested IDEs and added the command to install the yaml plugin in VScode. BTW I love that feature, as auto-completion and validation speed up the process a lot 😃 TY

Verified locally via

docker run --name mkdocs --rm -it -p 8000:8000 -e SITE_URL=http://localhost -v $(pwd)/source/mkdocs:/docs sq
uidfunk/mkdocs-material:9

open http://0.0.0.0:8000/developer-guide/json-schema/#getting-started

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[erwaxler]

Hi @mavogel , thank you for your contribution as well as your feedback! It's great to hear this feature has made it easier for developers to quickly and effectively interact with their LZA configuration files. I've gone ahead and incorporated this commit into the code base, this will be included in our next minor release. Thank you for your support of the Landing Zone Accelerator!