docs(streaming-files): split StreamableFile example into 2 parts.

Author: Eamonn McEvoy

content/techniques/streaming-files.md

@@ -31,17 +31,35 @@ Fastify, by default, can support sending files without needing to call `stream.p
 
 You can find a simple example of returning the `package.json` as a file instead of a JSON below, but the idea extends out naturally to images, documents, and any other file type.
 
-> info **hint** If the @Response parameter is present, it must have `{{ '{' }} passthrough: true {{ '}' }}`.
+```ts
+import { Controller, Get, StreamableFile } from '@nestjs/common';
+import { createReadStream } from 'fs';
+import { join } from 'path';
+
+@Controller('file')
+export class FileController {
+  @Get()
+  getFile(): StreamableFile {
+    const file = createReadStream(join(process.cwd(), 'package.json'));
+    return new StreamableFile(file);
+  }
+}
+```
+
+The default content type is `application/octet-stream`, if you need to customize the response you can use `res.set`.
+
+> info **hint** If the @Response parameter is present, it must have `{ passthrough: true }`.
 
 ```ts
-import { Controller, Get, StreamableFile, Response } from '@nestjs/common';
+import { Controller, Get, StreamableFile } from '@nestjs/common';
 import { createReadStream } from 'fs';
 import { join } from 'path';
 
 @Controller('file')
 export class FileController {
   @Get()
-  getFile(@Response({ passthrough: true }) res): StreamableFile {
+  @Response({ passthrough: true }) res,
+  getFile(): StreamableFile {
     const file = createReadStream(join(process.cwd(), 'package.json'));
     res.set({
       'Content-Type': 'application/json',
@@ -50,4 +68,4 @@ export class FileController {
     return new StreamableFile(file);
   }
 }
-```
+```