feat: Added documentation for applyTo selector

docs-js/orchestration/chat-completion.mdx

@@ -746,6 +746,79 @@
 });
 ```
 
+### ApplyTo Selector
+
+The `applyTo` property in the translation configuration allows you to selectively translate which messages or parts of messages in the conversation should be translated.
+This provides granular control over translation in multi-turn conversations.
+
+This selector is optional and allows specifying:
+
+- `category` - Can be either `placeholders` or `template_roles`;
+- `items` - Array of specific placeholder or role names to apply the translation to;
+- `sourceLanguage` (optional) - Source language for the items. If not specified, the detected language will be applied.
+
+When no `applyTo` selector is defined, the system translates all applicable content without selective filtering.
+For more information about this feature please refer to [this](https://help.sap.com/docs/sap-ai-core/sap-ai-core-service-guide/enhance-model-consumption-with-translation#loio152a5f4796f9493d98323786571356bf__section_rck_4gp_2hc) link.
+
+##### Placeholders
+
+The `placeholders` category allows translating specific placeholder values from the `placeholderValues` parameter of the `chatCompletion()` method.
+
+##### Template Roles
+
+The `template_roles` category allows translating template messages with specific message roles, such as `user`, `assistant`, or `system` messages in the prompt.
+
+```ts
+const inputTranslation = buildTranslationConfig('input', {
+  sourceLanguage: 'en-US',
+  targetLanguage: 'de-DE',
+  applyTo: [
+    {
+      category: 'placeholders',
+      items: ['country'],
+      sourceLanguage: 'en-US'
+    },
+    {
+      category: 'placeholders',
+      items: ['groundingRequest'],
+      sourceLanguage: 'de-DE'
+    }
+  ]
+});
+
+const outputTranslation = buildTranslationConfig('output', {
+  sourceLanguage: 'en-US',
+  targetLanguage: 'de-DE',
+  applyTo: [
+    {
+      category: 'template_roles',
+      items: ['user', 'assistant'],
+      sourceLanguage: 'de-DE'
+    }
+  ]
+});
+```
+
+#### Automatic Target Language Inference
+
+By detecting the source language from translation, the output translation can automatically respond in the user's original language.
+There is no need to specify a fixed target language, instead reference the `applyTo` item from the input translation.
+
+For more information check out [this](https://help.sap.com/docs/sap-ai-core/sap-ai-core-service-guide/enhance-model-consumption-with-output-translation-48be058d01bd4df2a82e5430561e6f44#automatic-target-language-inference) link.
+
+#### Chat History Control
+
+By default, chat history messages are translated.
+If chat history message translation is not necessary, set the `translateMessagesHistory` to `false`.
+
+```ts
+const translationConfig = buildTranslationConfig('input', {
+  sourceLanguage: 'de-DE',
+  targetLanguage: 'en-US',
+  translateMessagesHistory: false
+});
+```
+
 ## Use JSON Configuration from AI Launchpad
 
 If you already have an orchestration workflow created in your SAP AI Launchpad instance, you can either download the configuration as a JSON file or copy the JSON string in code to configure the orchestration client.