Add an example of messages

Author: mandel

docs/tutorial.md

@@ -65,6 +65,12 @@ Le mot 'world' en français est 'monde'.
 ```
 where everything after the `:` including it were generated by the model.
 
+
+Using the `input` field, we can also give a directly an array of messages (`role`/`content`) to the model ([file](https://github.com/IBM/prompt-declaration-language//blob/main/examples/tutorial/calling_llm_with_input_messages.pdl)):
+```yaml
+--8<-- "./examples/tutorial/calling_llm_with_input_messages.pdl"
+```
+
 ### Parameter defaults for watsonx Granite models
 
 PDL provides the following defaults for watsonx Granite models, when the following parameters are missing:

examples/tutorial/calling_llm_with_input.pdl

@@ -4,4 +4,3 @@ text:
 - model: watsonx/ibm/granite-20b-multilingual
   input: 
     Translate the word 'world' to French
-  

examples/tutorial/calling_llm_with_input_messages.pdl

@@ -0,0 +1,10 @@
+description: Hello world calling a model
+text:
+- "Hello, "
+- model: watsonx/ibm/granite-20b-multilingual
+  input:
+    array:
+    - role: system
+      content: You are a helpful assistant that is fluent in French.
+    - role: user
+      content: Translate the word 'world' to French