Appending maps to a map in Go

I am trying to build a map[string]map[string]string which will look something like this:

{ "notes": 
    {
    "Title":note.Title,
    "Body":note.Body,
    },
    {
    "Title":note.Title,
    "Body":note.Body,
    },
    {
    "Title":note.Title,
    "Body":note.Body,
    },
}

from a struct (notes) of structs (note)

I have thought of doing it like this:

for _, note := range notes {
		thisNote := map[string]string{
			"Title":note.Title,
			"Body":note.Body,
		}

		content["notes"] = append(content["notes"], thisNote)
}

But obviously that is not going to work because I am trying to append a map to a map rather than a slice.

Is there a really easy solution to this that I am missing?

Thanks to Running Wild for this answer, it was in a comment but I thought I would add it here for anyone trying to do the same thing.

The issue was that I needed to make a map[string][]map[string]string rather than a map[string]map[string]string

I'm pretty sure you can use a struct like this instead since mustache receives the data as an interface{}

func handler(w http.ResponseWriter, r *http.Request) {
    var data struct {
        Notes []*Note
    }

    notes := ...
    data.Notes = notes
    tmpl := ...
    templ.Render(data, w)
}