Merge pull request #618 from mikeal/patch-1

Adding iojs to README.

README.markdown

@@ -72,6 +72,10 @@ In place of a version pointer like "0.10", you can use the special default alias
     nvm use stable
     nvm run unstable --version
     
+If you want to install `io.js`:
+
+    nvm install iojs
+
 If you want to use the system-installed version of node, you can use the special default alias "system":
 
     nvm use system