In Kurzform/deutsch:
"https://www.yourdomain.com/sitemap.xml" soll in robots.txt und so muss man seine Sitemap nicht mehr an die grösseren Suchmaschinen übermitteln.
Did you know as of April 11th there was no longer a need to manually submit your sitemap to search engines. Last fall, the major search engines agreed on a sitemaps format. You can now add a simple line to your robots.txt file and let the engines know where your sitemap document resides on your site.
Robots.txt has traditionally been used in a more prohibitive fashion - by telling search engine spiders where not to go on your site. This latest sitemaps implementation of robots.txt however is telling the spiders where TO go.
Sitemaps are important and in the long run will help improve your website visibility in search results.