Animated gif has visual artifacts

[martinlindhe]

Issue description:

This animated gif seem to have some compression artifacts in some of the frames.

URL to the documentation page:

https://docs.godotengine.org/en/stable/tutorials/2d/2d_movement.html
and the image in question is

https://docs.godotengine.org/en/stable/_images/movement_8way.gif

[tetrapod00]

As a rule we're trying to use videos over GIFs now. So the fix for this would be to recapture this as a video.
For interested contributors:

• There is a guide on how to do that here https://docs.godotengine.org/en/stable/contributing/documentation/docs_image_guidelines.html#videos
• The code to recreate the GIF/video is already present in the page