📝 Review & adapt guidelines to reflect v1.0 upgrade

[dalito]

Observed in version

current, after merge of #229

Description

The HTML documentation still needs to be updated after switching the repository to the v1.0 formats and to voc4cat-tool 1.0.0.

• Describe new sheets in xlsx template and role of read-only sheets
• Adapt/extend description of columns in Concepts and Collection sheets
• Describe improve provenance support, ideally with examples
• Change screenshots to show new-style xlsx sheets.
• more?