title: go tool: no such tool "tour"
body: <p>I'm trying out Go for the first time. I was following <a href="https://tour.golang.org/welcome/3" rel="noreferrer">these docs</a> and wanted to run the go tour locally, but I haven't figured out how to get it to work.  </p>
  
  <p>Where is the tool "tour" supposed to be found?<br>
  I'm on OSX 10.11.3, and I installed Go via Homebrew<br>
  my Go entries in <code>.zshrc</code></p>
  
  <pre><code>export GOPATH=$HOME/code/Go
  export GOROOT=/usr/local/opt/go/libexec
  export PATH=$PATH:$GOPATH/bin
  export PATH=$PATH:$GOROOT/bin
  </code></pre>