docs(tutorial): explain how to upgrade dependencies

Related: angular/angular-seed#439

Author: gkalpak

docs/content/tutorial/index.ngdoc

@@ -282,6 +282,27 @@ the application as a whole is executing correctly. It is very common to run E2E
 a new commit of changes to a remote repository.
 
 
+### Updating dependencies
+
+To avoid surprizes, the versions of all dependencies listed in `package.json` are pinned to specific
+versions (this is what the [package-lock.json][package-lock] file is about). This ensures that the
+same version of a dependency is installed every time.
+
+If, however, you want to update one or more dependencies, you can use the `npm update` command:
+
+- When passed a package name (e.g. `npm update some-package`), it will update the specified package
+  to the latest version permitted by its version range (as specified in `package.json`). For
+  example, if `package.json` contains `"some-package": "1.2.x"`, it will be updated to the latest
+  1.2.x version, but not to 1.3.x.
+
+- When run without any arguments, `npm update` will update all packages listed as dependencies in
+  `package.json` to the latest version permitted by their specified version range.
+
+- Finally, you can request for a package to be updated to the latest version (regardless of its
+  version range in `package.json`), by appending `@latest` to the package's name:
+  `npm update some-package@latest`
+
+
 ### Common Issues
 
 <br />
@@ -336,5 +357,6 @@ Now that you have set up your local machine, let's get started with the tutorial
 [npm]: https://www.npmjs.com/
 [nvm]: https://github.com/creationix/nvm
 [nvm-windows]: https://github.com/coreybutler/nvm-windows
+[package-lock]: https://docs.npmjs.com/files/package-lock.json
 [protractor]: https://github.com/angular/protractor
 [selenium]: https://docs.seleniumhq.org/