update README.md

Author: mattn

README.md

@@ -10,9 +10,7 @@ go-sqlite3
 
 sqlite3 driver conforming to the built-in database/sql interface
 
-Supported Golang version:
-- 1.9.x
-- 1.10.x
+Supported Golang version: See .travis.yml
 
 [This package follows the official Golang Release Policy.](https://golang.org/doc/devel/release.html#policy)