FEATURE: Document new link editor for readthedocs

[mhsdesign]

The Neos UI ships with neos/neos-ui#3996 a new link editor. Its backwards-compatible to already set links and also supports the same options though in a different structure (see documentation).

Following legacy options should be rewritten to use the declaration in linkTypes instead. They will be upcasted (via neos/neos-ui#4037) at runtime if no new declaration in linkTypes is made. Using new and old syntax simultaneously will lead to old syntax being ignored fully.

• assets use linkTypes.Asset.enabled: false instead to disabled asset links
• nodes use linkTypes.Node.enabled: false instead to disabled asset links
• nodeTypes use linkTypes.Node.baseNodeType with a NodeType filter string instead
• startingPoint use linkTypes.Node.startingPoint instead
• placeholder obsolete finds no application in the new link editor can be safely removed

The anchor option for the inline editor to enable anchor support was removed. Instead anchors can be set via the "Advanced Options" to both Asset and Node links. For Web links the anchor is naturally part of the full link input at all times.

  inline:
    editorOptions:
      linking:
-       anchor: true
        title: true
        relNofollow: true
        targetBlank: true

Upgrade instructions

Review instructions

Checklist

• Code follows the PSR-2 coding style
• Tests have been created, run and adjusted as needed
• The PR is created against the lowest maintained branch
• Reviewer - PR Title is brief but complete and starts with FEATURE|TASK|BUGFIX
• Reviewer - The first section explains the change briefly for change-logs
• Reviewer - Breaking Changes are marked with !!! and have upgrade-instructions

[Sebobo]

Tried to build the docs locally but failed. Used a simple preview to at least verify the structure. Adjusted a few minor typos. Just wondered about the deprecation sentence.

Btw. you used a wild mix of tabs and spaces.