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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