You can already do that I use them as protection just back into the one corresponding size of your ship and im not trolling you can back your ship in, just pull up in line turn around with no sails open and hit the S key and you ship will back up slowly then just anchor and walla.
Now Im sure you ment like a dock button or something like that and it will auto put your ship there but I dont forsee that happening.
Hope this helps,