chore(docs): fix typo in image.mdx docs (#71647)
There was an extra backtick causing a format error.
https://nextjs.org/docs/app/api-reference/components/image#src
<img width="664" alt="image"
src="https://github.com/user-attachments/assets/2792e71b-f3a7-4790-80a0-eecb5210753a">
