Update challenge_12.md

Signed-off-by: Sanyam Jain <sanyam.jain-it-2k20-55@iips.edu.in>

Author: shivaylamba

Challenges/challenge_12.md

@@ -9,6 +9,6 @@ So focus for this challenge will be to practice the ``git rebase`` command. We s
 Ensure to practice the ``git rebase`` command by creating your own local git repository. You can checkout this guide: https://www.freecodecamp.org/news/git-squash-explained/
 
 Task: 
-1. Practice git rebase, and how to squash commit susing git rebase in your local projects 
+1. Practice git rebase, and how to squash commit using git rebase in your local projects 
 2. Once done, try to squash the commits in your pull request in the Challenge repository
 3. We also see a lot of challengers are not signing their commits. Refer to Challenge 10: https://github.com/scaleracademy/scaler-september-open-source-challenge/blob/main/Challenges/challenge_10.md and ensure to sign your commits.