Update modelfile.md to include `MESSAGE`

docs/modelfile.md

@@ -38,6 +38,7 @@ INSTRUCTION arguments
 | [`SYSTEM`](#system)                 | Specifies the system message that will be set in the template. |
 | [`ADAPTER`](#adapter)               | Defines the (Q)LoRA adapters to apply to the model.            |
 | [`LICENSE`](#license)               | Specifies the legal license.                                   |
+| [`MESSAGE`](#message)               | Specify message history.                                       |
 
 ## Examples
 
@@ -205,6 +206,19 @@ LICENSE """
 """
 ```
 
+### MESSAGE
+
+The `MESSAGE` instruction allows you to specify a message history for the model to use when responding:
+
+```modelfile
+MESSAGE user Is Toronto in Canada?
+MESSAGE assistant yes
+MESSAGE user Is Sacramento in Canada?
+MESSAGE assistant no
+MESSAGE user Is Ontario in Canada?
+MESSAGE assistant yes
+```
+
 ## Notes
 
 - the **`Modelfile` is not case sensitive**. In the examples, uppercase instructions are used to make it easier to distinguish it from arguments.