[Documentation]:  Split ngx-i18n introduction page into two sections

The `ngx-i18n` page needs to be divided into a `For business` and a `For developers` section.

- In the `For business` section, we explain that the i18n package is used for translation management in a modular and performant way, with ways to prevent translations from being loaded for users that do not have access to those items.
- In the `For developers` section we use the existing documentation