Explain 3D range references in the docs

[warpech]

Description

HyperFormula supports 3D range references (ranges spanning across multiple sheets). This is useful in many ways, as presented in multiple advanced Excel tutorials found online, e.g.:

• https://www.ablebits.com/office-addins-blog/2015/12/09/excel-3d-reference-formula/
• https://support.microsoft.com/en-us/office/create-a-3-d-reference-to-the-same-cell-range-on-multiple-worksheets-40ca91ff-9dcb-4ad1-99d2-787d0bc888b6

We should present a viable use case in the Guide.

I am not sure if the name "3D range reference" is a correct one.

Links

Type of issue

• [x] Missing documentation
• [ ] Error in the documentation
• [ ] Request for a demo
• [ ] Request for a tutorial, guide etc.
• [ ] Other issues, suggestions or ideas