Doc: Add alternate text for Qt Sensors images


Alternate text (alt text) improves the documentation experience for
screen readers and for other accessibility tools. Also enable
reportmissingalttextforimages to enforce alt text on future images.

Task-number: QTBUG-135098
Pick-to: 6.11 6.12
Change-Id: Ib87cf5fbba38f438ab30342301c94391a39a2041
Reviewed-by: Lorn Potter <lorn.potter@qt.io>
commite3cfd737e5c9dad7a79e977ca476a08b5e06eccf
parentd9a2e9b5e01d1413a0e5c1d25ee19ef544140fab
authorJerome Pasion <jerome.pasion@qt.io>
committerJerome Pasion <jerome.pasion@qt.io>
commit timeWed, 17 Jun 2026 10:48:02 +0000