docs-bug(Sidenav): Autosize sidenav example uses drawer instead of sidenav

### Documentation Feedback

The sidenav component's "Autosize sidenav" example is incorrect: it uses mat-drawer rather than sidenav.


### Affected documentation page

https://material.angular.io/components/sidenav/examples

Open the affected Sidenav examples page and inspect the “Autosize sidenav” example, focusing on the component used in its markup. Update the example so it uses the sidenav component rather than the drawer component, then verify that the rendered example and its displayed source match the intended Sidenav example.

Written by the indexing model from the issue text.