title: Create a git tag with submodule
body: <p>Small question about git submodule.</p>
  
  <p>Assume I have a <code>projectA</code>, and it have a submodule maybe called <code>moduleA</code>.</p>
  
  <p>Then I create a tag in <code>projectA</code>, <code>tagA</code>, then I may have some new commits for <code>projectA</code> or <code>moduleA</code> also, and then I want to go back to the <code>tagA</code>, using <code>git checkout tagA</code>.</p>
  
  <p>The problem is <code>projectA</code> go back to <code>tagA</code>, but <code>moduleA</code> not.</p>
  
  <p>Do you know how can make this?</p>