docs(core): ensure readme variable names are consistent

Author: mcous

packages/svelte-core/README.md

@@ -101,7 +101,10 @@ const { baseElement, container, component, rerender, unmount } = render(
 Validate options and prepare document elements for rendering.
 
 ```ts
-const { baseElement, container, mountOptions } = setup(options, renderOptions)
+const { baseElement, container, mountOptions } = setup(
+  componentOptions,
+  setupOptions
+)
 ```
 
 | Argument           | Type                                                    | Description                                   |
@@ -120,7 +123,7 @@ const { baseElement, container, mountOptions } = setup(options, renderOptions)
 Mount a Svelte component into the document.
 
 ```ts
-const { component, unmount, rerender } = mount(Component, options)
+const { component, unmount, rerender } = mount(Component, mountOptions)
 ```
 
 | Argument       | Type                                      | Description                                  |