docs(workspaces): update using npm section

Added examples of using `npm init` to bootstrap a new workspace and a
section on how to add/manage dependencies to workspaces.

PR-URL: #3392
Credit: @ruyadorno
Close: #3392
Reviewed-by: @wraithgar

Author: ruyadorno

docs/content/using-npm/workspaces.md

@@ -21,7 +21,7 @@ single **workspace**, meaning it's a nested package within the current local
 file system that is explicitly defined in the [`package.json`](/configuring-npm/package-json#workspaces)
 `workspaces` configuration.
 
-### Installing workspaces
+### Defining workspaces
 
 Workspaces are usually defined via the `workspaces` property of the
 [`package.json`](/configuring-npm/package-json#workspaces) file, e.g:
@@ -63,6 +63,49 @@ structure of files and folders:
    `-- package.json
 ```
 
+### Getting started with workspaces
+
+You may automate the required steps to define a new workspace using
+[npm init](/commands/npm-init). For example in a project that already has a
+`package.json` defined you can run:
+
+```
+npm init -w ./packages/a
+```
+
+This command will create the missing folders and a new `package.json`
+file (if needed) while also making sure to properly configure the
+`"workspaces"` property of your root project `package.json`.
+
+### Adding dependencies to a workspace
+
+It's possible to directly add/remove/update dependencies of your workspaces
+using the [`workspace` config](/using-npm/config#workspace).
+
+For example, assuming the following structure:
+
+```
+.
++-- package.json
+`-- packages
+   +-- a
+   |   `-- package.json
+   `-- b
+       `-- package.json
+```
+
+If you want to add a dependency named `abbrev` from the registry as a
+dependency of your workspace **a**, you may use the workspace config to tell
+the npm installer that package should be added as a dependency of the provided
+workspace:
+
+```
+npm install abbrev -w a
+```
+
+Note: other installing commands such as `uninstall`, `ci`, etc will also
+respect the provided `workspace` configuration.
+
 ### Using workspaces
 
 Given the [specifities of how Node.js handles module resolution](https://nodejs.org/dist/latest-v14.x/docs/api/modules.html#modules_all_together) it's possible to consume any defined workspace
@@ -138,4 +181,5 @@ Will run the `test` script in both `./packages/a` and `./packages/b`.
 * [npm install](/commands/npm-install)
 * [npm publish](/commands/npm-publish)
 * [npm run-script](/commands/npm-run-script)
+* [config](/using-npm/config)