replace 'image' attribute by 'model' in 'models' definitions (#22992)

<!--Delete sections as needed -->

## Description
Fix the Compose models examples which are wrongly referencing to `image`
instead of `model` to define the LLM to use

## Related issues or tickets
N/A
<!-- Related issues, pull requests, or Jira tickets -->

## Reviews

<!-- Notes for reviewers here -->
<!-- List applicable reviews (optionally @tag reviewers) -->

- [ ] Technical review
- [x] Editorial review
- [ ] Product review

Signed-off-by: Guillaume Lours <[email protected]>

Author: aevesdocker

content/manuals/ai/compose/model-runner.md

@@ -40,7 +40,7 @@ services:
 
 models:
   smollm2:
-    image: ai/smollm2
+    model: ai/smollm2
 ```
 
 ### How it works
@@ -70,7 +70,7 @@ services:
 
 models:
   smollm2:
-    image: ai/smollm2
+    model: ai/smollm2
 ```
 
 With this configuration, your `my-chat-app` service will receive:

content/manuals/ai/compose/models-and-compose.md

@@ -42,7 +42,7 @@ services:
 
 models:
   llm:
-    image: ai/smollm2
+    model: ai/smollm2
 ```
 
 This example defines:
@@ -56,7 +56,7 @@ Models support various configuration options:
 ```yaml
 models:
   llm:
-    image: ai/smollm2
+    model: ai/smollm2
     context_size: 1024
     runtime_flags:
       - "--a-flag"
@@ -87,9 +87,9 @@ services:
 
 models:
   llm:
-    image: ai/smollm2
+    model: ai/smollm2
   embedding-model:
-    image: ai/all-minilm
+    model: ai/all-minilm
 ```
 
 With short syntax, the platform automatically generates environment variables based on the model name:
@@ -116,9 +116,9 @@ services:
 
 models:
   llm:
-    image: ai/smollm2
+    model: ai/smollm2
   embedding-model:
-    image: ai/all-minilm
+    model: ai/all-minilm
 ```
 
 With this configuration, your service receives:
@@ -142,7 +142,7 @@ services:
 
 models:
   llm:
-    image: ai/smollm2
+    model: ai/smollm2
 ```
 
 Docker Model Runner will:
@@ -163,9 +163,9 @@ services:
 
 models:
   llm:
-    image: ai/smollm2
+    model: ai/smollm2
     # Cloud-specific configurations
-    labels:
+    x-cloud-options:
       - "cloud.instance-type=gpu-small"
       - "cloud.region=us-west-2"
 ```