Add custom tokens

[earakel]

Hey @jorge-campo, sending this for your review!

[jorge-campo]

We discussed the next steps and changes during our call.

Let's clarify first the terminology and what we understand by "custom tokens". This way, we can approach the article's updates with a fresh and better understanding.

Thanks, @shamisem !

[earakel]

Thanks for your review Jorge! This branch is quite old, so I feel it would be easier to simply close it and create a new one than fix all of those merge conflicts. I will apply your comments and submit the new version.

[jorge-campo]

Hi @shamisem – When you close a branch and start working on a different one, add a comment to keep track of this fact. See #663, as an example. Thanks!