docs(react): add file path

Author: thetaPC

docs/react/your-first-app/3-saving-photos.md

@@ -17,7 +17,7 @@ We’re now able to take multiple photos and display them in a photo gallery on
 
 ## Filesystem API
 
-Fortunately, saving them to the filesystem only takes a few steps. Begin by creating a new class method, `savePicture()`, in the `usePhotoGallery()` method.
+Fortunately, saving them to the filesystem only takes a few steps. Begin by creating a new class method, `savePicture()`, in the `usePhotoGallery()` method in `usePhotoGallery.ts`.
 
 ```ts
 import { useState, useEffect } from 'react';

versioned_docs/version-v7/react/your-first-app/3-saving-photos.md

@@ -17,7 +17,7 @@ We’re now able to take multiple photos and display them in a photo gallery on
 
 ## Filesystem API
 
-Fortunately, saving them to the filesystem only takes a few steps. Begin by creating a new class method, `savePicture()`, in the `usePhotoGallery()` method.
+Fortunately, saving them to the filesystem only takes a few steps. Begin by creating a new class method, `savePicture()`, in the `usePhotoGallery()` method in `usePhotoGallery.ts`.
 
 ```ts
 import { useState, useEffect } from 'react';