Add field for canonical link to encourage blog cross posting

If blog post writers would have the ability to set a canonical link on the Dapr blog that points to the original article on their own blog, I expect more writers would be open to cross posting here.

How-to: https://discourse.gohugo.io/t/how-to-add-cannonical-url-to-a-blog/34670

I'm happy to pick up this issue myself.