fix: simplify hello guidebook to remove top-level markdown tabs

Author: starpit

plugins/plugin-client-default/notebooks/hello.md

@@ -7,23 +7,11 @@ layout:
         maximized: true
 ---
 
-=== "Run a Job"
-    ```shell
-    ---
-    execute: now
-    outputOnly: true
-    maximize: true
-    ---
-    codeflare terminal task
-    ```
-
-=== "Terminal"
-    ```shell
-    ---
-    execute: now
-    outputOnly: true
-    maximize: true
-    ---
-    codeflare terminal shell
-    ```
-
+```shell
+---
+execute: now
+outputOnly: true
+maximize: true
+---
+codeflare terminal task
+```