Update tutorial to mention the new "rush add" command

pages/developer/modifying_package_json.md

@@ -4,20 +4,47 @@ title: Modifying package.json
 navigation_source: docs_nav
 ---
 
-Let's say you need to add a new dependency on a library "**example-lib**".  Without Rush, you would do something like this:  `npm install --save example-lib`.  Currently Rush doesn't have a handy command for this (it's in our backlog, PR's welcome!).
-
-Fortunately there's a pretty great alternative if you use Visual Studio Code as your editor. Simply start typing `"example-lib":` into the **package.json** file, and VS Code will query the NPM registry and show autocomplete suggestions for the latest version number.  Easy!
-
-After saving the file, then we need Rush to update your shrinkwrap file and perform the installation:
+Let's say you need to add a new dependency on a library "**example-lib**".  Without Rush, you would do something like this:
 
 ```sh
-# Always run this command after editing package.json
-$ rush update
-
-# If there are changes to the shrinkwrap file, commit them to your branch
-$ git commit -m "Ran 'rush update'"
+# DON'T DO THIS IN A RUSH REPO:
+~/my-repo$ cd apps/my-app
+~/my-repo/apps/my-app$ npm install --save example-lib
 ```
 
+In a Rush repo, you should instead use the [rush add]({% link pages/commands/rush_add.md %}) command:
+
+```sh
+~/my-repo$ cd apps/my-app
+
+# Add "example-lib" as a dependency of "my-app", and then automatically run "rush update":
+~/my-repo/apps/my-app$ rush add example-lib
+```
+
+The `rush add` command can also be used to update the version of an existing dependency:
+
+```sh
+# Update "my-app" to use "example-lib" version "~1.2.3":
+~/my-repo/apps/my-app$ rush add example-lib@1.2.3
+
+# Or if you want the version specifier "^1.2.3":
+~/my-repo/apps/my-app$ rush add example-lib@1.2.3 --caret
+
+# If any other projects in the repo are using "example-lib", you can update them all together:
+~/my-repo/apps/my-app$ rush add example-lib@1.2.3 --make-consistent
+
+```
+
+The [command-line help]({% link pages/commands/rush_add.md %}) for `rush add` describes other options that you can use to customize the behavior.
+
+
+> **Tip: A cool VS Code feature**
+>
+> By the way, if you use Visual Studio Code as your editor, another option is to simply edit the **package.json** file directly. If you start typing `"example-lib":`, VS Code will automatically query the NPM registry and show autocomplete suggestions for the latest published version.  For simple additions, this can be even quicker than `rush add`.
+>
+> If you modify **package.json** manually, don't forget to run `rush update` afterwards.
+
+
 ## Upgrading to newer versions of your NPM packages
 
 Today, Rush does not yet have an integrated equivalent of `npm update` or [npm-check-updates](https://www.npmjs.com/package/npm-check-updates).  So you if you want to update the SemVer patterns across all your package.json files, you'll need to use an external tool.