This commit moves the third-party-libraries.html topic to the qmake
documentation. The topic is renamed and links to it are corrected.
See also: 623150
Task-number: QTBUG-132504
Pick-to: 6.9
Change-Id: I711400d887b7e4894021b0433eb1cd61dfdd5349
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>