Here is the rendered code
<div>dfdbfbdfbdfbdfbdfbfb gdfgfggtbrtb
<a href="www.github.com" target="_blank"> rtrtrt
</a>
<p></p>
</div>
I get this, when i click in the hyperlinked text
https://myapp.io/www.github.com
Remember to use HTTP protocol with external links, if you don't use HTTP before the link, it will be considered as local resource link. In your above mentioned code you should use
<a href="http://www.github.com">Github</a>
Instead of
<a href="www.github.com">Github</a>