You can make a block for that and insert it in the text editor (XhtmlString property).

Just one property needed on the block type:

[ContentType]
public class FileListBlock : BlockData
{
    [UIHint(UIHint.MediaFolder)]
    public virtual ContentReference FolderPath { get; set; }
}

Then you can use IContentRepository to get the children (files):

var contentRepo = ServiceLocator.Current.GetInstance<IContentRepository>();

IEnumerable<MediaData> files = contentRepo.GetChildren<MediaData>(myBlockContent.FolderPath);

In your block view you just render <ul> with links to the files:

<ul>
    @foreach (var file in files)
    {
        <li><a href="@Url.ContentUrl(file.ContentLink)">@file.Name</a>
    }
</ul>