Docker.md

@@ -4,7 +4,7 @@ To build or run Autoware, we strongly recommend using our Docker environments. A
 
 The preferred computing environment is listed below:
 
-* Ubuntu 16.04 / 18.04
+* Ubuntu 18.04
 * Intel Core i7 (preferred), Intel Core i5, Intel Atom, AMD Ryzen 7 (preferred), AMD Ryzen 5
 * 16GB to 32GB of RAM
 * More than 30GB of Storage (SSD recommended)