Add demo video link to README

Added a demo video link to the README.

Author: sakshamwithweb

README.md

@@ -1,6 +1,7 @@
 ## LearnCPP-StudyMode
 ***Remove blockers for learncpp.com***
 
+**Demo**: [Video](https://hc-cdn.hel1.your-objectstorage.com/s/v3/92e1afc1be5556d0_learncpp-study.mode.mp4)
 
 -----------------
 ### Setup Steps
@@ -18,4 +19,4 @@ That's it, now it will automatically do rest of the work!
 ### Advanced(for me) tasks:
 - [ ] Remove unusual comments only
 - [ ] Don't even load useless things..
-- [ ] Give a checkbox to control.
+- [ ] Give a checkbox to control.