docs: change image path to silence warning, #518

[andretchen0]

Closes #518

Problem

When running pnpm run docs:dev a warning was being printed to the terminal about an image path:

5:05:06 PM [vitepress] hmr update /guide/index.md
Assets in public directory cannot be imported from JavaScript.
If you intend to import that asset, put the file in the src directory, and use /src/playground.png instead of /public/playground.png.
If you intend to use the URL of that asset, use /playground.png?url.
Files in the public directory are served at the root path.
Instead of /public/playground.png, use /playground.png.

Solution

This updates the image path to remove the warning.

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