Hint at the reactivity limitation of array methods in the api docs

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

@@ -56,6 +56,8 @@ To change component state and trigger a re-render, just assign to a locally decl
 
 Update expressions (`count += 1`) and property assignments (`obj.x = y`) have the same effect.
 
+Because Svelte's reactivity is triggered only by assignments, using array methods like push and splice won't automatically cause updates. Options for getting around the limitation can be found in the [tutorial](https://svelte.dev/tutorial/updating-arrays-and-objects).
+
 ```html
 <script>
 	let count = 0;