[Doc] Align style in readme for language packages

[Patys]

When you follow guideline in https://github.com/marmelab/ra-supabase you go to the following pages:

• https://github.com/marmelab/ra-supabase/tree/main/packages/ra-supabase
• https://github.com/marmelab/ra-supabase/tree/main/packages/ra-supabase-core
• https://github.com/marmelab/ra-supabase/tree/main/packages/ra-supabase-ui-materialui
• and language packages,

all follow the style when yarn is first, then npm. In language packages it is the other way round, npm and then yarn.

• https://github.com/marmelab/ra-supabase/tree/main/packages/ra-supabase-language-english
• https://github.com/marmelab/ra-supabase/tree/main/packages/ra-supabase-language-french

So when you copy-paste commands it is easy to make a mistake. Let's align all the readmes to one style.

[fzaninotto]

Thanks!