title: "Git add ." can not stage files in subfolder
body: <p>I am just starting to learn git commands and came across a strange issue. 
  On my local mac, I have a repo in directory "1st-repo" with only 2 things: (1)"README.md" (2)"myFolder" subfolder containing a bunch of files</p>
  
  <p>To stage all my files at once, I entered directory "<code>1st-repo</code>" and ran command "<code>git add .</code>" like shown below:</p>
  
  <p><a href="https://i.stack.imgur.com/vIBoR.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/vIBoR.jpg" alt="git add"></a></p>
  
  <p>However, after this, when I run <code>git status</code>, it still shows <code>myFolder</code> not staged.<br>
  Can someone help me figure out why?</p>
  
  <p><a href="https://i.stack.imgur.com/crqBF.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/crqBF.jpg" alt="git status"></a></p>