title: How to update mkdir in order to install express-generator without warnings?
body: <p>I was going to install express-generator on windows computer. I used this<br><br>
  <code>npm install -g express-generator</code><br><br>
  command in cmd and it gave me this<br><br> <strong>npm WARN deprecated mkdirp@0.5.1: Legacy versions of mkdirp are no longer supported. Please update to mkdirp 1.x. (Note that the API surface has changed to use Promises in 1.x.)</strong> warning. Then I used<br><br><code>npm install mkdirp@1</code><br><br>and successfully installed <strong>mkdirp@1.0.4</strong> version. CMD confirmed it showing me this message <br><br><strong>+ mkdirp@1.0.4
  updated 1 package and audited 1 package in 1.981s
  found 0 vulnerabilities</strong><br><br>
  But unfoutunately when I try to reinstall express-generator using <code>npm install -g express-generator</code>, cmd shows me the same warning. Exactly the same warning. How Can I update mkdirp?? Help Me..</p>