title: append svg:text below each rect element
body: <p>Are having a hard time to figure out this problem.</p>
  
  <p>i.e. if has a svg</p>
  
  <pre><code>&lt;svg&gt;
  &lt;rect id='1'&gt;&lt;/rect&gt;
  &lt;rect id='2'&gt;&lt;/rect&gt;
  &lt;rect id='3'&gt;&lt;/rect&gt;
  &lt;rect id='4'&gt;&lt;/rect&gt;
  &lt;/svg&gt;
  </code></pre>
  
  <p>how can I append a svg:text below each rect using selectAll and enter function?
  (actually using json data set)</p>
  
  <p>I want to result such below...</p>
  
  <pre><code>&lt;svg&gt;
  &lt;rect id='1'&gt;&lt;/rect&gt;
  **&lt;text&gt;text here...&lt;/text&gt;**
  &lt;rect id='2'&gt;&lt;/rect&gt;
  **&lt;text&gt;text here...&lt;/text&gt;**
  &lt;rect id='3'&gt;&lt;/rect&gt;
  **&lt;text&gt;text here...&lt;/text&gt;**
  &lt;rect id='4'&gt;&lt;/rect&gt;
  **&lt;text&gt;text here...&lt;/text&gt;**
  &lt;/svg&gt;
  </code></pre>