Add test string-with-whitespace-but-unquoted and fix corresponding doc

README.md

@@ -93,12 +93,13 @@ LESS | JS
 ---- | ----
 "hello world" | '"hello world"'
 
-*Note:* strings that contain a whitespace but are not quoted will not be quoted.
-I'm not even sure if this is even valid LESS syntax in most cases.
+*Note:* strings that contain a whitespace but are not quoted will result in the
+words being joined with a comma.
+See the section "Multiple values being juxtaposed" below for an explanation.
 
 LESS | JS
 ---- | ----
-hello world | 'hello world'
+hello world | 'hello, world'
 
 ### Pixels will result in plain numbers
 

test/string-with-whitespace-but-unquoted/index.less

@@ -0,0 +1 @@
+@str: hello world;

test/string-with-whitespace-but-unquoted/test.js

@@ -0,0 +1,5 @@
+var assert = require('assert');
+
+module.exports = function (importResult) {
+  assert.deepEqual(importResult.str, 'hello, world');
+};