title: add first line to second line but separated with a tab
body: <p>I am using  grep -B2 "average / return" /home/me/Desktop/file ,
  how do I get the desired one-liner output where the first line
  is added to the second line but separated from second line with a tab?</p>
  
  <pre><code>some words here
  average / return 1,2 4 5,6 
  --
  other words here
  average / return 4,3 7 9,4
  --
  </code></pre>
  
  <p>desired output:</p>
  
  <pre><code>some words here     average / return 1,2 4 5,6
  --
  other words here    average / return 4,3 7 9,4
  --
  </code></pre>