docs: add git switch commands to Git cheatsheet

[harsh6125]

What I changed

While going through the Git cheatsheet, I noticed that the branch section uses git checkout for switching to an existing branch and creating a new branch.

I updated these two examples to use the dedicated git switch commands:

• git switch my_branch — switch to an existing branch
• git switch -c new_branch — create and switch to a new branch

The reason for this change is that git switch is specifically designed for branch switching and creation, making the commands clearer and easier to understand for people learning Git. git checkout is still a valid Git command, but it is used for several different purposes, whereas git switch makes the branch-related operation more explicit.

I kept the change limited to these two examples in the Git cheatsheet.