Resolve "adjust schema for validation of yaml files"

Closes #120 (closed) Closes em_glossary_owl#11 (closed)

ToDo's

• remove allcaps in comment of https://codebase.helmholtz.cloud/em_glossary/em_glossary/-/blob/main/terms/TEM_backscattering.yaml?ref_type=heads#L15
• In some yaml files, the key is comment_en and in others comments_en, see this vs that
• Multiple comment files still have symbol that forces yaml to parse as string instead of a list, see here
• simplyfy template to drop language codes
• adjust yaml files according to new template