Using www along with non-www for main domain in multisite installation

I have a multisite installation that runs on Nginx.

In my site's configuration file, I have set the server block as:

server{
        listen 80 default_server;
        server_name example.com *.example.com;
        server_name_in_redirect off;

        access_log   /var/log/nginx/example.com.access.log;
        error_log    /var/log/nginx/example.com.error.log;

        root /var/www/example.com/htdocs;
        index index.php;

        if (!-e $request_filename) {
                rewrite /wp-admin$ $scheme://$host$uri/ permanent;
                rewrite ^(/[^/]+)?(/wp-.*) $2 last;
                rewrite ^(/[^/]+)?(/.*\.php) $2 last;
        }

        location / {
                try_files $uri $uri/ /index.php?$args;
        }
}

Right now, whenever I enter www.example.com in the browser, I get redirected to example.com.

However, I want example.com to redirect to www.example.com.

I also plan to use HTTPS with www.example.com

What else do I need to add to my configuration file to make this happen?