fix(guide): simplify directory structure

guide/english/javascript/tutorials/decrement-a-number-with-javascript/index.md

@@ -0,0 +1,12 @@
+---
+title: Decrement a Number with JavaScript
+---
+You can easily decrement or decrease a variable by `1` with the `--` operator.
+
+    i--;
+
+is the equivalent of
+
+    i = i - 1;
+
+**Note:** The entire line becomes `i--;`, eliminating the need for the equal sign.