Translation: Update index.md

[K3v123]

simplified the words using "vibrant" instead. used illustrate instead of demonstrate because I'm thinking the image "illustrates" the concept.

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• [x] This PR represents the translation of a single, complete document, or contains only bug fixes.
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[QiLOL]

Looks great, thanks for the contribution!

[K3v123]

thanks guys for the review!