Inside this directory, there is a routes directory. Open it up. Take a look at routes/index.js (index.js is used by Node as the default file in any directory).
There is line that tells the Express router that any url starting with '/all' will be handled by routes/api/index.js:
router.use('/api', require('./api'))
Notice and open the routes/api/index.js file.
Notice the search route, which is created using the defaultSearchRoute factory function. There are also auth and CRUD routes installed out-of-the-box. You are free to add more or remove some if required for your project.
There are a number of configuration options for the default routes, which are documented in that file. You can read more about the default routes in the grove-default-routes README.