3rd day content added

Author: smilegupta

README.md

@@ -24,6 +24,11 @@ I here follow an mechanism of learn by practising and making lots of projects an
       - Video Stream of the session [:movie_camera:](https://www.youtube.com/watch?v=TKy1NQtb5UY)
       - Running Notes [:computer:](https://del.dog/react-day2.txt)
 
+   - Day3 
+     - Topic Covered: Creeating a React Toggle Switch (using useEffect and useState) and Styled Component and Deployment using vercel
+     - Video Stream of the session [:movie_camera:](https://youtu.be/E9gzlhKnxjI)
+     - Source Code [:computer:](https://github.com/smilegupta/Dark-Light-mode)
+      
 
  ## Want me to check your learning and clear your doubts or review code?