Merge pull request #12095 from infodiver/patch-1

fix a typo

docs/manual/buildTools/Testing-with-NPM.html

@@ -144,7 +144,7 @@ $ npm install three --save-dev
 				<li>
 					Mocha will look for tests in test/, so let's
 					<code>
-					$ mkdir test.
+					$ mkdir test
 					</code>
 				</li>