[WIP] Improve documentation for links and references - working on it ...

[sypets]

• [x] Start with restructuring: LinkHandler API is subpage of LinkBrowser, makes no sense: https://docs.typo3.org/m/typo3/reference-coreapi/master/en-us/ApiOverview/LinkBrowser/Index.html. Use a different start page, e.g. Links & References
• [x] Move Softreferences in menu to be subpage of "Links & References"
• [ ] clarify terms
• [ ] update information, see #1491

clarify terms

• links

• references

• soft references

• what is a linkhandler

• t3 URI format specifically

• what is difference between links and soft references?

• what is difference between soft references and other references (hard references), see https://docs.typo3.org/m/typo3/reference-coreapi/master/en-us/ApiOverview/SoftReferences/Index.html

look at existing docs and write missing pieces:

outline:

• introduction to links in TYPO3
  • explain some basic terms, e.g.
    • difference between links, soft references, "hard" references or relations
    • explain t3 URI format
  • how does it work - e.g. resolving of links, editing links in BE etc.
  • extendability, how can extensions "hook into" functionality
• link handler
  • linkhandler API (already exist, but nowhere it is explained, what is a linkhandler ...)
• link browser
  • link browser API
• soft references
  • softref parsers https://docs.typo3.org/m/typo3/reference-coreapi/master/en-us/ApiOverview/SoftReferences/Index.html
  • reference index
• refer to LinkValidator API