Clarify create-next-app question wording (#66157)

### Why?

The current wording leaves room for questions/misinterpretations like:

- What does "use `src/`" mean? Does this affect my build, like compile
`src/*.ts` to `lib/*.js`?
- Oh, I can customize import aliases to use @ for project root instead
of doing relative everywhere? I'll choose Yes!

I think the proposed wording clarifies ^

---------

Co-authored-by: Sam Ko <sam@vercel.com>

docs/01-getting-started/01-installation.mdx

@@ -28,10 +28,10 @@ What is your project named? my-app
 Would you like to use TypeScript? No / Yes
 Would you like to use ESLint? No / Yes
 Would you like to use Tailwind CSS? No / Yes
-Would you like to use `src/` directory? No / Yes
+Would you like your code inside a `src/` directory? No / Yes
 Would you like to use App Router? (recommended) No / Yes
 Would you like to use Turbopack for `next dev`?  No / Yes
-Would you like to customize the default import alias (@/*)? No / Yes
+Would you like to customize the import alias (`@/*` by default)? No / Yes
 What import alias would you like configured? @/*
 ```
 

docs/02-app/02-api-reference/06-create-next-app.mdx

@@ -36,10 +36,10 @@ What is your project named?  my-app
 Would you like to use TypeScript?  No / Yes
 Would you like to use ESLint?  No / Yes
 Would you like to use Tailwind CSS?  No / Yes
-Would you like to use `src/` directory?  No / Yes
+Would you like your code inside a `src/` directory?  No / Yes
 Would you like to use App Router? (recommended)  No / Yes
 Would you like to use Turbopack for `next dev`?  No / Yes
-Would you like to customize the default import alias (@/*)?  No / Yes
+Would you like to customize the import alias (`@/*` by default)?  No / Yes
 ```
 
 Once you've answered the prompts, a new project will be created with the correct configuration depending on your answers.

packages/create-next-app/index.ts

@@ -376,7 +376,7 @@ async function run(): Promise<void> {
           onState: onPromptState,
           type: 'toggle',
           name: 'srcDir',
-          message: `Would you like to use ${styledSrcDir}?`,
+          message: `Would you like your code inside a ${styledSrcDir}?`,
           initial: getPrefOrDefault('srcDir'),
           active: 'Yes',
           inactive: 'No',
@@ -440,7 +440,7 @@ async function run(): Promise<void> {
           onState: onPromptState,
           type: 'toggle',
           name: 'customizeImportAlias',
-          message: `Would you like to customize the default ${styledImportAlias} (${defaults.importAlias})?`,
+          message: `Would you like to customize the ${styledImportAlias} (${defaults.importAlias} by default)?`,
           initial: getPrefOrDefault('customizeImportAlias'),
           active: 'Yes',
           inactive: 'No',