Add Duolingo to the list of pre-defined sites

[zacyu]

intended for links to Duolingo user profiles, e.g. https://www.duolingo.com/profile/gugu.ke

• [x] tested locally and the button renders as the following

[tvx-matt]

Looks Good. I definitely agree that this should be added.

[lastsamurai26]

First of all, I would like to thank you for your pull and your commitment

we are currently working on a new version and are not accepting any new buttons at the moment, but you are welcome to provide us your button as a custom block.

But I'll keep an eye on your two pulls

https://github.com/LinkStackOrg/example-block https://github.com/LinkStackOrg/linkstack-blocks/wiki