Sync readme.md and index.d.ts

Author: decimoseptimo

index.d.ts

@@ -225,10 +225,15 @@ export interface StringifyOptions {
 	- `comma`: Serialize arrays by separating elements with comma:
 
 		```
-		import queryString = require('query-string');
+		const queryString = require('query-string');
 
 		queryString.stringify({foo: [1, 2, 3]}, {arrayFormat: 'comma'});
 		//=> 'foo=1,2,3'
+
+		queryString.stringify({foo: [1, null, '']}, {arrayFormat: 'comma'});
+		//=> 'foo=1,,'
+		// Note that typing information for null values is lost
+		// and `.parse('foo=1,,')` would return `{foo: [1, '', '']}`.
 		```
 
   - `separator`: Serialize arrays by separating elements with character:

readme.md

@@ -231,7 +231,7 @@ queryString.stringify({foo: [1, 2, 3]}, {arrayFormat: 'comma'});
 
 queryString.stringify({foo: [1, null, '']}, {arrayFormat: 'comma'});
 //=> 'foo=1,,'
-// Note that typing information for null values are lost
+// Note that typing information for null values is lost
 // and `.parse('foo=1,,')` would return `{foo: [1, '', '']}`.
 ```