Doc: Add Qt for INTEGRITY to Reference page

Documentation page reference-overview.html#platform-reference
is missing Qt for INTEGRITY. Add it to the list.
Update also the linked page title.

Change-Id: Ia25295cfb47a40dfdaa172c81764c6c4caa66d86
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>

doc/src/platforms/platform-notes-integrity.qdoc

@@ -28,9 +28,11 @@
 
 /*!
     \page platform-notes-integrity.html
-    \title Platform Notes - INTEGRITY
+    \title Qt for INTEGRITY
     \contentspage Platform Notes
     \keyword INTEGRITY
+    \ingroup supportedplatform
+    \brief Platform support for INTEGRITY.
 
     From Qt 5.9 onwards, the Green Hills Software
     \l {http://www.ghs.com/products/rtos/integrity.html} {INTEGRITY}