documentation of QOpenGLTexture

In the Qt documentation for this class, nothing is said about the image format. Storing images in a format other than QImage::Format_RGBA8888 in an array and create a lot of textures makes reconversion of the image, which greatly affects performance.

Solutions:

1. Write about this in doc
2. Works with another formats

 [QOpenGLTexture Class | Qt OpenGL|https://doc.qt.io/Qt-6/qopengltexture.html#QOpenGLTexture-1]