Change 'default value' to 'initial value' to set expectations about b…

…ehaviour, for issue sveltejs#4442

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

@@ -42,13 +42,13 @@ Svelte uses the `export` keyword to mark a variable declaration as a *property*
 
 ---
 
-You can specify a default value for a prop. It will be used if the component's consumer doesn't specify the prop on the component. Note that whenever a specified prop is removed by the consumer, the value is set to `undefined` rather than the default value.
+You can specify an initial value for a prop. It will be used if the component's consumer doesn't specify the prop on the component. Note that whenever a specified prop is removed by the consumer, the value is set to `undefined` rather than the initial value.
 
-In development mode (see the [compiler options](docs#svelte_compile)), a warning will be printed if no default is provided and the consumer does not specify a value. To squelch this warning, ensure that a default is specified, even if it is `undefined`.
+In development mode (see the [compiler options](docs#svelte_compile)), a warning will be printed if no initial value is provided and the consumer does not specify a value. To squelch this warning, ensure that an initial value is specified, even if it is `undefined`.
 
 ```html
 <script>
-	export let bar = 'optional default value';
+	export let bar = 'optional initial value';
 	export let baz = undefined;
 </script>
 ```