docs: fixed link to the code style guide

docs/manual/introduction/Code-style-guide.html

@@ -16,7 +16,7 @@
 			if you are adding code to the library or examples then you must follow this guide.<br /><br />
 
 			You can find details
-			<a href="https://github.com/mrdoob/three.js/wiki/Mr.doob%27s-Code-Style%E2%84%A2">here</a>.
+			<a href="https://github.com/mrdoob/three.js/wiki/Mr.doob%27s-Code-Style%E2%84%A2" target="_blank">here</a>.
 		</div>
 	</body>
 </html>