Update article.md

In the section "String concatenation with binary +", the example of 2 + 2 + "1" was given, but there was no example for when the first operand is a string.

Author: Heikrana

1-js/02-first-steps/08-operators/article.md

@@ -106,6 +106,11 @@ alert(2 + 2 + '1' ); // "41" and not "221"
 
 Here, operators work one after another. The first `+` sums two numbers, so it returns `4`, then the next `+` adds the string `1` to it, so it's like `4 + '1' = 41`.
 
+```js run
+alert('1' + 2 + 2); // "122" and not "14"
+```
+Here, the first operand is a string, the compiller treats the other two operands as string too. The `2` gets concatinated to `'1'`, so it's like `'1' + 2 = "12"` and `"12" + 2 = "122"`
+
 The binary `+` is the only operator that supports strings in such a way. Other arithmetic operators work only with numbers and always convert their operands to numbers.
 
 Here's the demo for subtraction and division: