fix(guide): simplify directory structure

guide/english/javascript/get-timestamp/index.md

@@ -0,0 +1,8 @@
+---
+title: Get Timestamp
+---
+You can use `Date.now()` to get the current timestamp in milliseconds.
+
+You can easily convert the timestamp to seconds like this: `Math.floor(Date.now() / 1000)`
+
+If your browser does not support `Date.now()`, you can use `new Date().getTime()` to get the timestamp in milliseconds.