A \target defines a global doc linking target across all Qt modules,
and they may interfere with link targets local to module documentation.
As we no longer link as heavily to qmake manual after moving to CMake,
remove the \target commands. The section titles remain as valid link
targets; arguably, duplicating a \section1 title with an identical
\target name was unnecessary in any case.
Replace all \l command arguments that used the \target for linking
with the actual section title.
Pick-to: 6.6 6.5
Fixes: QTBUG-114073
Change-Id: I6e595a77268cbd6ddb5d004501bc6df178c3883d
Reviewed-by: Andreas Eliasson <andreas.eliasson@qt.io>
Reviewed-by: Paul Wicking <paul.wicking@qt.io>
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>