Document how to plug Cunningham inputs with Formik & React Hook Form

[jbpenrath]

Purpose

We need to demonstrate how to use Cunningham inputs with popular React form libraries (React Hook Form & Formik).

Proposal

Add within a documentation a dedicated part to explain that our inputs components are compatible with RHF & Formik. This documentation should also contain a story to demonstrate an implementation with RHF.

[NathanVss]

We are good with RHF, we just need to add Formik :)