title: How to install Webpacker with Rails
body: <p>I'm trying to install Webpacker to be able to launch a Yarn server.  I'm on Rails 5 and the gem is installed.</p>
  <p>When I run</p>
  <pre><code>bundle exec rails webpacker:install
  </code></pre>
  <p>I get:</p>
  <pre><code>&gt;&gt; rails aborted!
  Don't know how to build task 'webpacker:install' (see --tasks)
  bin/rails:15:in `require'
  bin/rails:15:in `&lt;main&gt;'
  (See full trace by running task with --trace)
  </code></pre>
  <p>The command doesn't seem to exist.</p>