Replace "Sisphean labour" for readability reasons (#22961)

While this really nice use of grammar , I feel like maybe just saying “ Feels like a task that can never be completed” in place of “ Sisyphean” would reduce the cognitive load in this part of the Doc

docs/docs/using-gatsby-image.md

@@ -29,7 +29,7 @@ But creating optimized images for websites has long been a thorny problem. Ideal
 - Use the “blur-up” technique or a “traced placeholder” SVG to show a preview of the image while it loads
 - Hold the image position so your page doesn’t jump while the images load
 
-Doing this consistently across a site feels like Sisyphean labor. You manually optimize your images and then… several images are swapped in at the last minute or a design-tweak shaves 100px of width off your images.
+Doing this consistently across a site feels like a task that can never be completed. You manually optimize your images and then… several images are swapped in at the last minute or a design-tweak shaves 100px of width off your images.
 
 Most solutions involve a lot of manual labor and bookkeeping to ensure every image is optimized.