Doc: Fix documentation warnings for Qt OpenGL

Use a custom module header for the documentation build that pulls in
also QtOpenGLWidgets' headers.

Fixes: QTBUG-88275
Change-Id: I4e1144b179a124b01114de24cc183289fa05fb33
Reviewed-by: Paul Wicking <paul.wicking@qt.io>

src/opengl/doc/QtOpenGLDoc

@@ -0,0 +1,2 @@
+#include <QtOpenGL/QtOpenGL>
+#include <QtOpenGLWidgets/QtOpenGLWidgets>

src/opengl/doc/qtopengl.qdocconf

@@ -1,6 +1,10 @@
 include($QT_INSTALL_DOCS/global/qt-module-defaults.qdocconf)
 include($QT_INSTALL_DOCS/config/exampleurl-qtbase.qdocconf)
 
+# Use a custom module header that pulls in also QtOpenGLWidgets
+includepaths += .
+moduleheader = QtOpenGLDoc
+
 # Name of the project which must match the outputdir. Determines the .index file
 project = QtOpenGL
 

src/opengl/doc/src/qtopengl-index.qdoc

@@ -42,7 +42,8 @@
     wrapper around the platform-dependent GLX (version 1.3 or later),
     WGL, or AGL C APIs. Although the basic functionality provided is very
     similar to Mark Kilgard's GLUT library, applications can use the
-    other \l{Qt modules} to implement the rest of the user interface.
+    other \l{All Modules}{Qt modules} to implement the rest of the user
+    interface.
 
     The \l{Qt OpenGL C++ Classes} page gives an overview over the available classes
     in this module.