Update comment for SignInButton

[ahsanatzapier]

Description

• We updated useAuth to use signInWithPopup instead of signInWithRedirect, but the comment wasn't updated.
• This pull request updates the comment.

Acceptance Criteria

• Comment for SignInButton reflects the actual behavior of the sign-in workflow.

Type of Changes

documentation

Updates

Before

• SignInButton comment stated user would be redirected to sign-in.

After

• SignInButton comment states a popup will open for the sign-in.

Testing Steps / QA Criteria

• Verify that the comment reflects the accurate behavior of the sign-in flow.
• Ensure the SignInButton opens a popup for Google OAuth sign-in and successfully signs in the user, closing the popup after the process.

[deeheber]

Thanks for taking care of this.

[github-actions]

Visit the preview URL for this PR (updated for commit a10a758):

https://tcl-75-smart-shopping-list--pr20-useauth-comments-upd-wal2gs1t.web.app

_{(expires Sun, 18 Aug 2024 17:21:48 GMT)}

_{🔥 via Firebase Hosting GitHub Action 🌎}

_{Sign: 1f1fd53c369e1fa31e15c310aa075b4e8f4f8dde}