The stable manual link will give you the new Lubuntu 26.04 LTS Manual.
The LTS manual link will give the older Lubuntu 24.04 LTS Manual.
The development manual link will show work on the upcoming stonking release (26.10), but don’t look for changes there yet.
( Lubuntu 25.10 manual has been replaced with 26.04 manual; so 25.10 manual can no longer be viewed online )