Leading slashes in .gitignore

This is a friendly reminder to keep leading slashes in mind in .gitignore files.

The other day, I pulled down a project and couldn't get the CSS to build because files were missing. It turned out another developer created a new resources/css/vendor directory to override styles for third-party components. A fine name, but vendor was ignored so they were quietly missing from the repository. We updated .gitignore to use /vendor instead and all was well.

# Ignores all vendor files
vendor
 
# Only ignores vendor at the project root
/vendor