docs: Added a spoiler image.

README.md

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 [![Build and Lint (frontend)](https://github.com/kkomelin/sui-dapp-starter/actions/workflows/build_and_lint.yaml/badge.svg)](https://github.com/kkomelin/sui-dapp-starter/actions/workflows/build_and_lint.yaml)
 [![Discord chat](https://img.shields.io/discord/1237259509366521866.svg?logo=discord&style=flat-square)](https://discord.com/invite/HuDPpXz4Hx)
 
+![Spoiler](https://repository-images.githubusercontent.com/794883099/4b66c35f-9412-47c7-ab1c-67e26346295f)
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 ## Motivation
 
 The official [e2e Sui starter template](https://github.com/MystenLabs/sui/tree/main/sdk/create-dapp) is a good starting point but it's very basic. While working with it, I came up with a list of [DX improvements](https://github.com/kkomelin/sui-dapp-starter/wiki), which I ended up wrapping into a separate starter template. And here it is.