From the Visual Studio Code Setup page:
Tip: If you want to run VS Code from the terminal by simply typing 'code', VS Code has a command, Shell Command: Install 'code' command in PATH, to add 'code' to your $PATH variable list.
After installation, launch VS Code. Now open the Command Palette (F1 or ?+?+P on Mac) and type
shell command
to find theShell Command: Install 'code' command in PATH
command.After executing the command, restart the terminal for the new $PATH value to take effect. You'll be able to simply type 'code .' in any folder to start editing files in that folder.