docs: ng add configures project in cwd

Author: jbogarthyde

packages/angular/cli/commands/add.md

@@ -1,8 +1,9 @@
-Adds the npm package for a published library to your workspace, and configures your default
-app project to use that library, in whatever way is specified by the library's schematic.
+Adds the npm package for a published library to your workspace, and configures
+the project in the current working directory (or the default app if you are
+not in a project directory) to use that library, as specified by the library's schematic.
 For example, adding `@angular/pwa` configures your project for PWA support:
 ```bash
 ng add @angular/pwa
 ```
 
-The default app project is the value of `defaultProject` in `angular.json`. 
+The default app project is the value of `defaultProject` in `angular.json`.