[TASK] Overhaul data / gettext chapter (#1165)

* [TASK] Overhaul data / gettext chapter

* Use confvals instead of aspects
* Correct indentation
* Give headlines to examples
* Some small changes where content didnt make sense

* Update Documentation/Functions/Data.rst

Co-authored-by: Chris Müller <[email protected]>

* Update Documentation/Functions/Data.rst

Co-authored-by: Chris Müller <[email protected]>

* Update Documentation/Functions/Data.rst

Co-authored-by: Chris Müller <[email protected]>

* Update Documentation/Functions/Data.rst

Co-authored-by: Chris Müller <[email protected]>

* Update Documentation/Functions/Data.rst

Co-authored-by: Chris Müller <[email protected]>

* Apply suggestions from code review

Co-authored-by: Chris Müller <[email protected]>

* [TASK] Overhaul PAGE chapter

* Use confvals instead of tables
* Correct indentation
* Give headlines to examples
* Introduce a toc for the properties

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Co-authored-by: Chris Müller <[email protected]>