Add 6.40 as latest release

Author: dpiparo

doc/selectversion.js

@@ -31,7 +31,7 @@ function url2version(patharr) {
 // The latest release. NOT necessarily equal to latest-stable, as stable releases are only
 // once every two versions.
 // >>> CHANGE THIS WHEN A NEW VERSION IS RELEASED! (stable or not) <<<
-const LATEST_VERSION = 638; 
+const LATEST_VERSION = 640; 
 const LATEST_VERSION_IS_STABLE = LATEST_VERSION % 4 === 0;
 const LATEST_STABLE = LATEST_VERSION - 2 * !LATEST_VERSION_IS_STABLE;
 const FIRST_VERSION = 610;