UPDATE:
There are some reports that this method does not work consitently with higher versions of Android and IOS. We can format the link using the initial method by @sabanna but direct the share to whatsapp this way;
<a href="whatsapp://send?text=" title="Share On Whatsapp" onclick="window.open('whatsapp://send?text=%20Take%20a%20look%20at%20this%20awesome%20page%20-%20' + encodeURIComponent(document.URL)); return false;"></a>
This will take care of pulling all dynamic titles and meta content, including the page’s meta image if set in the designer.