Fix typo in CONTRIBUTING.md

Author: OmarKimo

CONTRIBUTING.md

@@ -19,7 +19,7 @@ Install Git:
 1. Fork this repository on Github.
 2. Clone it onto your computer by opening terminal and running the command $ git clone https ://github.com/{your username}/ACM-ICPC-Algorithms.git
 3. Use the actual name of the repository to change into that directory (eg. *$ cd repository*) and create and switch to a new branch by the following command: $ git checkout -b new-branch
-4. After modifying existing files or adding new files to the project, add them locally to your repository using $ gid add -A command where A is the file
+4. After modifying existing files or adding new files to the project, add them locally to your repository using $ git add -A command where A is the file
 5. Add a short message about what you contributed for with the git commit command. For eg. $ git commit -m "Fixed documentation typos"
 6. Now use the command $ git push --set-upstream origin new-branch to push the changes to the current branch of your forked repository
 7. Now you can create a Pull Request with the chosen branch as new-branch