Merge pull request #1809 from leviding/patch-4

Add bigint to 1-js/02-first-steps/17-javascript-specials/article.md

Author: iliakan

1-js/02-first-steps/17-javascript-specials/article.md

@@ -81,9 +81,10 @@ let x = 5;
 x = "John";
 ```
 
-There are 7 data types:
+There are 8 data types:
 
 - `number` for both floating-point and integer numbers,
+- `bigint` for integer numbers of arbitrary length,
 - `string` for strings,
 - `boolean` for logical values: `true/false`,
 - `null` -- a type with a single value `null`, meaning "empty" or "does not exist",