title: Highcharts tooltip date format when using pointFormat
body: <p>hi i am working on highcharts with net transactions on y-axis and type datetime on x-axis. i have shown month and date on x-axis point label as (jan 2016) and want to show the same date format on tooltip. but its showing full date with day as well like "Monday, jan 1, 2016.</p>
  
  <p>here is my js code.</p>
  
  <pre><code>tooltip: {
          headerFormat: '&lt;span style="font-size:10px"&gt;{point.x:%Y-%m}&lt;/span&gt;&lt;table&gt;',
          pointFormat: '&lt;tr&gt;&lt;td style="color:{series.color};padding:0;font-size:11px;"&gt;{series.name}: &lt;/td&gt;' +
          '&lt;td style="padding:0"&gt;&lt;b&gt;{point.y:,.0f}&lt;/b&gt;&lt;/td&gt;&lt;/tr&gt;',
          footerFormat: '&lt;/table&gt;',
          shared: true,
          useHTML: true
      },
  </code></pre>
  
  <p>Thanks for any help  </p>