Doc: Fix documentation warnings for Qt OpenGL

Task-number: QTBUG-86295
Change-Id: I4fff2d61f8f0513181150954440c9357acf73c1d
Reviewed-by: Paul Wicking <paul.wicking@qt.io>

src/opengl/doc/qtopengl.qdocconf

@@ -19,7 +19,8 @@ sourcedirs  += .. \
 exampledirs += ../../../examples/opengl \
                . \
                snippets \
-               ..
+               .. \
+               ../../gui/doc/snippets
 imagedirs   += images \
                ../../../examples/opengl/doc/images
 

src/opengl/qopenglversionfunctions.cpp

@@ -247,9 +247,9 @@ void QAbstractOpenGLFunctionsPrivate::removeExternalFunctions(QOpenGLContext *co
 
     A pointer to an object of the class corresponding to the version and
     profile of OpenGL in use can be obtained from
-    QOpenGLContext::versionFunctions(). If obtained in this way, note that
-    the QOpenGLContext retains ownership of the object. This is so that only
-    one instance need be created.
+    QOpenGLVersionFunctionsFactory::get(). If obtained in this way, note that
+    the QOpenGLContext retains ownership of the object. This is so that the
+    instance can be cached and shared.
 
     Before calling any of the exposed OpenGL functions you must ensure that the
     object has resolved the function pointers to the OpenGL functions. This
@@ -266,7 +266,7 @@ void QAbstractOpenGLFunctionsPrivate::removeExternalFunctions(QOpenGLContext *co
     profile. This is obviously a lot easier to debug than undefined behavior
     at run time.
 
-    \sa QOpenGLContext::versionFunctions()
+    \sa QOpenGLVersionFunctionsFactory::get()
 */
 /*!
    Constructs a QAbstractOpenGLFunctions object.

src/opengl/qopenglversionfunctionsfactory.cpp

@@ -161,6 +161,14 @@ static QAbstractOpenGLFunctions *createFunctions(const QOpenGLVersionProfile &ve
 #endif
 }
 
+/*!
+    \class QOpenGLVersionFunctionsFactory
+    \inmodule QtOpenGL
+    \since 6.0
+    \brief Provides access to OpenGL functions for a specified version and
+           profile.
+*/
+
 /*!
     \fn static T *QOpenGLVersionFunctionsFactory::get(QOpenGLContext *context)