feat: update prompt

Author: Angular2Guy

backend/src/main/java/ch/xxx/aidoclibchat/usecase/service/FunctionService.java

@@ -44,7 +44,7 @@ public record JsonResult(String author, List<JsonBook> books) {
 	private final String promptStr = """
 			Make sure to have a parameter when calling a function.
 			If no parameter is provided ask the user for the parameter.
-			Create a summary for each book based on the function response subject.
+			Create a summary of two full sentences based on the subject property for each book and put it in the function response subject.
 
 			User Query:
 			%s