How do I setup an assets feed using the FeedMe plugin?
I believe they've added the documentation you're wanting here: https://verbb.io/craft-plugins/feed-me/docs/content-mapping/field-types#assets

Assets
Accepts single or multiple values. You should supply the filename only, excluding the full path to the asset, but including the filename. If you're uploading remote assets, you'll need to produce fully-qualified URLs.
Additional Options

Upload remote asset (choose how to handle existing assets - Replace/Keep/Ignore)
Inner-element fields


&lt;Asset&gt;my_filename.jpg&lt;/Asset&gt;
// Or
&lt;Assets&gt;
    &lt;Asset&gt;my_filename.jpg&lt;/Asset&gt;
    &lt;Asset&gt;my_other_filename.jpg&lt;/Asset&gt;
&lt;/Assets&gt;

//
// When selecting upload
//
&lt;Asset&gt;http://mydomain.com/my_filename.jpg&lt;/Asset&gt;

// Or
&lt;Assets&gt;
    &lt;Asset&gt;http://mydomain.com/my_filename.jpg&lt;/Asset&gt;
    &lt;Asset&gt;http://mydomain.com/my_other_filename.jpg&lt;/Asset&gt;
&lt;/Assets&gt;