update gith url code example

Example 1: git overwrite urlk

# Overwriting an existing git url:
git remote set-url origin <git_url>

Example 2: git remote chage url

git remote -v
# View existing remotes
# origin  https://github.com/user/repo.git (fetch)
# origin  https://github.com/user/repo.git (push)

git remote set-url origin https://github.com/user/repo2.git
# Change the 'origin' remote's URL

git remote -v
# Verify new remote URL
# origin  https://github.com/user/repo2.git (fetch)
# origin  https://github.com/user/repo2.git (push)