Docs: Exporting function expression vs declaration

Current docs give the impression that functions can not be default values for props. Suggestion to make the distinction between expressions and declarations clearer.

site/content/docs/01-component-format.md

@@ -48,10 +48,13 @@ Svelte uses the `export` keyword to mark a variable declaration as a *property*
 	// are immediately available
 	console.log(foo, bar);
 	
-	// function declarations cannot be set externally,
-	// but can be accessed from outside
-	export function instanceMethod() {
-		alert(foo);
+	// Function expressions can also be props
+	export let format = (number) => (number.toFixed(2));
+
+	// Function declarations are added as methods
+	// on the component, rather than props
+	export function greetMethod() {
+		alert(`I'm a <${this.constructor.name}>!`);
 	}
 
 	// you can also use export { ... as ... } to have