Translations keys in textbook

[korgan00]

Let us use the translations in another way that we are doing right now.
The $translate functionality gets a string and uses it as a key to finding a translation in the selected current language. If the translation doesn't exist, it uses the key as the string. So, for English, we use the key, and we don't have a translation file.

If we change the copy at some point, we will need to change every single translation file.

Maybe we can set up a key-generator rule something as we do in BEM: component__section__text-description
And then create the English translations of that key to the official copy text.