doc: remove obsolete external link

The addons documentation links to an external node-qt repo as
a production example. That repo hasn't been updated in over
five years. This commit removes the link.

PR-URL: #28326
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

doc/api/addons.md

@@ -306,9 +306,6 @@ console.log(addon.hello());
 // Prints: 'world'
 ```
 
-Please see the examples below for further information or
-<https://github.com/arturadib/node-qt> for an example in production.
-
 Because the exact path to the compiled Addon binary can vary depending on how
 it is compiled (i.e. sometimes it may be in `./build/Debug/`), Addons can use
 the [bindings][] package to load the compiled module.