multiple_resolutions.rst: Remove confusing stretch.png graphic

[jpaugh]

Remove confusing stretch.png graphic, which does not correspond to the available 4.x stretch modes, nor is it referred to by any of the surrounding text. In fact, the actual stretch modes behave quite differently than what this graphic implies.

[Sauermann]

I agree, that this picture doesn't help to describe the different stretch modes. When removing the link to the picture, you should probably also delete the picture img/stretch.png itself. It doesn't seem to be used anywhere else.

[jpaugh]

you should probably also delete the picture img/stretch.png itself.

@Sauermann Good idea, thanks! I have deleted that image, although I left the corresponding SVG in place. Perhaps someone will want to edit that into a usable image, later. It seems like it corresponds to 3.x stuff, maybe?

[Calinou]

Please remove both the SVG and PNG, as the image will have to be redone from scratch to be more descriptive anyway. If someone really needs the SVG, they can browse through Git history to get to it :slightly_smiling_face:

[mhilbrunner]

Thanks for contributing! This has been superseded by https://github.com/godotengine/godot-docs/pull/9049.