docs: Change "ng run build:ssr" to "npm run build:ssr" in universal.md (

angular#51192)

PR Close angular#51192

aio/content/guide/universal.md

@@ -357,7 +357,7 @@ Now, on every HTTP request made as part of rendering the application on the serv
 |:---                                                                                                        |:---     |
 | <code-example format="shell" language="shell"> npm run dev:ssr </code-example>                            | Similar to [`ng serve`](cli/serve), which offers live reload during development, but uses server-side rendering. The application runs in watch mode and refreshes the browser after every change. This command is slower than the actual `ng serve` command.                                                                                                                                                  |
 | <code-example format="shell" language="shell"> ng build &amp;&amp; ng run app-name:server </code-example> | Builds both the server script and the application in production mode. Use this command when you want to build the project for deployment.                                                                                                                                                                                                                                                                     |
-| <code-example format="shell" language="shell"> npm run serve:ssr </code-example>                          | Starts the server script for serving the application locally with server-side rendering. It uses the build artifacts created by `ng run build:ssr`, so make sure you have run that command as well. <div class="alert is-helpful"> **NOTE**: <br /> `serve:ssr` is not intended to be used to serve your application in production, but only for testing the server-side rendered application locally. </div> |
+| <code-example format="shell" language="shell"> npm run serve:ssr </code-example>                          | Starts the server script for serving the application locally with server-side rendering. It uses the build artifacts created by `npm run build:ssr`, so make sure you have run that command as well. <div class="alert is-helpful"> **NOTE**: <br /> `serve:ssr` is not intended to be used to serve your application in production, but only for testing the server-side rendered application locally. </div> |
 | <code-example format="shell" language="shell"> npm run prerender </code-example>                          | Used to prerender an application's pages. Read more about prerendering [here](guide/prerendering).                                                                                                                                                                                                                                                                                                            |
 
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