User guide translations

[romicolman]

Description

Professional translators will adapt the ODE user guide to Spanish, Portuguese and French.

Note: the docs translation will need to include https://starlight.astro.build/guides/i18n/

@sapetti9: I know you are handling this, but I also assign this to myself and @roll for the implementation part.

[sapetti9]

Let me know once the guides are ready to be translated, so I can export them to text files and send them to the translators.

[guergana]

There aren't any translations in the current state of the main branch left to sync for now. @sapetti9 @romicolman