feat: update docs where create-plugin is used with new --select plugin

Signed-off-by: Sayak Mukhopadhyay <mukhopadhyaysayak@gmail.com>

docs/tutorials/journey.md

@@ -28,7 +28,7 @@ organization to easily install and add to their Backstage installation.
 # 1. A New Plugin
 
 Sam chooses to develop this plugin in a standalone project and creates a new
-plugin using `npx @backstage/cli create-plugin`, which detects that it's not
+plugin using `npx @backstage/cli new --select plugin`, which detects that it's not
 being run in an existing project and therefore creates a separate plugin repo.
 
 Spinning up the frontend with `yarn start`, Sam goes to work with getting the

docs/tutorials/quickstart-app-plugin.md

@@ -29,8 +29,8 @@ title: Adding Custom Plugin to Existing Monorepo App
 
 # The Skeleton Plugin
 
-1. Start by using the built in creator. From the terminal and root of your
-   project run: `yarn create-plugin`
+1. Start by using the built-in creator. From the terminal and root of your
+   project run: `yarn new --select plugin`
 1. Enter a plugin ID. I used `github-playground`
 1. When the process finishes, let's start the backend:
    `yarn --cwd packages/backend start`