Fix no implicit this deprecation in docs-demo component

[nickschot]

There was a missing this in the DocsDemo component making it fail to compile with ember-source v4+.

[RobbieTheWagner]

@nickschot I think this should be @class, but I'm not 100% sure. I don't see class defined in the JS for the component though.

[nickschot]

Both works for classic components 😅 I'm fine with either here.

[miguelcobain]

Would be nice to see this released for all of those wanting to use addon-docs with ember 4+. :D

[RobbieTheWagner]

@miguelcobain hmm, I am pretty sure I have passing tests for all my addons using addon docs, so it's odd that I am not seeing this. Happy to do a release though

[RobbieTheWagner]

4.2.2 has been released

[miguelcobain]

Well, the tests pass with ember 4, that's true.
I was referring to running the dummy app with ember 4. I got runtime errors because of this (I believe this was the cause).

[nickschot]

Yep! Same. There's more stuff to update, but as far as I could see this was the only really breaking thing for running the dummy app.

[RobbieTheWagner]

@miguelcobain @nickschot I would love help updating the docs to be angle bracket and anything else you might see that needs updating, if you have the time ❤️