add a git ignore code example

Example 1: git global ignore

#Create your global ignore file like a normal .gitignore
#in your home folder.
git config --global core.excludesfile /path/to/home/.gitignore
#Your git now exclude any file declared in that .gitignore
#It's useful for hide your IDE's folder (.idea, .vscode, ...)

Example 2: create gitignore

# creates gitignore file
$ touch .gitignore