Remove out-of-date Cocoa known issues page.
Remove out-of-date Cocoa known issues page.

This page is not linked from anywhere, and its content is horribly
out-of-date.

Task-number: 251420
Reviewed-by: nrc
(cherry picked from commit c138c9e80acabcf1d9a712a7ebd2b2a7d6135d8b)

Conflicts:

	doc/src/qtcocoa-known-issues.qdoc

pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,RLovelett/qt,igor-sfdc/qt-wk,radekp/qt,radekp/qt,KDE/qt,igor-sfdc/qt-wk,igor-sfdc/qt-wk,igor-sfdc/qt-wk,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,KDE/qt,pruiz/wkhtmltopdf-qt,radekp/qt,KDE/qt,pruiz/wkhtmltopdf-qt,radekp/qt,igor-sfdc/qt-wk,RLovelett/qt,radekp/qt,KDE/qt,RLovelett/qt,igor-sfdc/qt-wk,RLovelett/qt,igor-sfdc/qt-wk,KDE/qt,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,RLovelett/qt,KDE/qt,KDE/qt,igor-sfdc/qt-wk,radekp/qt,RLovelett/qt,pruiz/wkhtmltopdf-qt,radekp/qt,pruiz/wkhtmltopdf-qt,RLovelett/qt,RLovelett/qt,igor-sfdc/qt-wk,igor-sfdc/qt-wk,RLovelett/qt,radekp/qt,radekp/qt,pruiz/wkhtmltopdf-qt,radekp/qt,RLovelett/qt,RLovelett/qt,pruiz/wkhtmltopdf-qt,KDE/qt