title: rCharts-How to add axis lables and Headings to NVD3 chart
body: <p>I am exploriing rCharts. I got stuck while adding Lables to Y axis and Headings. I am new to rCharts. </p>
  
  <p>This is my sample code</p>
  
  <pre><code>require(rCharts)
  n2 &lt;- nPlot(Hours ~ Month, group = "Task", data = cars, type = "multiBarChart",
  height = 900, width = 1110)
  n2$xAxis(axisLabel = 'Year and Month')
  n2
  </code></pre>
  
  <p>Please help.</p>