docs: Fix typo in getting-started/project-structure (#55035)

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- Fix typo in [Next.js Project Structure: Top-level
files](https://nextjs.org/docs/getting-started/project-structure#top-level-files)
- It's common to create it as `next-env.d.ts` without dots.

docs/01-getting-started/02-project-structure.mdx

@@ -30,7 +30,7 @@ This page provides an overview of the file and folder structure of a Next.js pro
 | [`.env.development`](/docs/app/building-your-application/configuring/environment-variables) | Development environment variables       |
 | [`.eslintrc.json`](/docs/app/building-your-application/configuring/eslint)                  | Configuration file for ESLint           |
 | `.gitignore`                                                                                | Git files and folders to ignore         |
-| `.next-env.d.ts`                                                                            | TypeScript declaration file for Next.js |
+| `next-env.d.ts`                                                                             | TypeScript declaration file for Next.js |
 | `tsconfig.json`                                                                             | Configuration file for TypeScript       |
 | `jsconfig.json`                                                                             | Configuration file for JavaScript       |
 | `postcss.config.js`                                                                         | Configuration file for Tailwind CSS     |