Documenting text functions and improving documentation outline

[gmischler]

In the context recent changes to various text functions (most recently #343 / #350) it has come up that there is no in-depth explanation of those functions and their differences (let alone the new positioning options) other than in the docstrings. Since I've modifying some of that functionality already, I probably should also add such a page, though in a seperate PR to keep things manageable.
In addition, while looking through the docs, I found that the TOC seems to have grown a lot over time without anyone adding much structure to it, which makes it quite hard to find any specific information. I tried to play around with it a bit and this is the most reasonable structure I could come up with:

• Tutorial
  • English
  • Français
  • Deutsch
  • ...
• Page Layout
  • Page Format and Orientation
  • Margins
  • Templates
  • Tables
• Text Content
  • Adding Text (new)
  • Line Breaks
  • Page Breaks
  • Text Styling
  • Unicode
  • Emojis, Symbols & Dingbats
• Graphics Content
  • Images
  • Shapes
  • Barcodes
  • Drawing
  • SVG
  • Charts & Graphs (formerly "Maths")
• PDF Features
  • Links
  • Metadata
  • Annotations
  • Presentation Mode
  • Document Outline & Table of Contents
• Processing Web Content
  • HTML
  • Web2Py
• Reading and Postprocessing
  • pdfrw
  • Borb
• Development
  • Development Guidelines
  • Logging
• API
• FAQ

Any objections when I modify it that way, or any better ideas? There are a few items that could go in several places.
Do I understand this right, that the documentation outline is defined in mkdocs.yml? Is there an easy way to test its processing locally?

[Lucas-C]

Wow, that's a great plan, thanks @gmischler !

No objection at all, I've been thinking aboutre-structuring the docs' ToC for a few months, without taking the time to do it so far. Much appreciated 😊

I think some page contents are maybe a bit outdated (Unicode & Web2Py for example) but they could be edited later on.

Go on, please submit a PR! 🙏