More detailed data documentation

[mdahlhausen]

Fixes #4947

This is a minor change to the data paragraph in the mainpage documentation. It makes loose reference to the DataEnums.hpp, but doesn't link to some important data enumerations,

The links to Vector.hpp, Matrix.hpp, and DataEnums.hpp appear broken, and this PR does not fix those.

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• Perform a Code Review on GitHub
• Code Style, strip trailing whitespace, etc.
• All related changes have been implemented: model changes, model tests, FT changes, FT tests, VersionTranslation, OS App
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[jmarrec]

Fix the vector matrix links

[jmarrec]

Thanks @mdahlhausen !