title: Concat of two list using LINQ
body: <p>I have two list list1 and list2</p>
  
  <p>List1 contains</p>
  
  <pre><code>1   a
  2   b
  3   c
  4   d
  </code></pre>
  
  <p>List2 contains</p>
  
  <pre><code>3   c
  4   d
  5   e
  </code></pre>
  
  <p>I want following list using LINQ</p>
  
  <pre><code>1   a
  2   b
  3   c
  4   d
  5   e
  </code></pre>