use shopify cli instead of npm (#2771)

Author: billfienberg

Diff for: packages/ui-extensions/docs/surfaces/admin/staticPages/examples/deploy.sh

@@ -2,6 +2,6 @@
 cd my-app
 
 # deploy your app and its extensions:
-npm run deploy
+shopify app deploy
 
 # follow the steps to deploy

Diff for: packages/ui-extensions/docs/surfaces/admin/staticPages/examples/getting-started.sh

@@ -1,10 +1,10 @@
 # create an app if you don't already have one:
-npm init @shopify/app@latest --name my-app
+shopify app init --name my-app
 
 # navigate to your app's root directory:
 cd my-app
 
 # generate a new extension:
-npm run generate extension
+shopify app generate extension
 # follow the steps to create a new
 # extension in ./extensions.