Doc: Update polar view documentation with an image and new example


Task-number: QTBUG-147042
Change-Id: Iab832c60ce6b6d88aa28a6a708c167baea759702
Reviewed-by: Xavier BESSON (Personal) <developer@xavi-b.fr>
Reviewed-by: Sami Varanka <sami.varanka@qt.io>
commit668a4a20e02e282e099285390fe3f72494df2f98
parent8e423277f823454f10d0edc9936800003a5c6826
authorAlexei Cazacov <alexei.cazacov@qt.io>
committerAlexei Cazacov <alexei.cazacov@qt.io>
commit timeFri, 18 Sep 2026 06:35:53 +0000