Modify: [EN]->[FR] Translating guidelines and recommendations

[harsha509]

Description

Translating below docs to french

1. Index.fr.md
2. avoid_sharing_state.fr.md
3. consider_using_a_fluent_api.fr.md

Types of changes

• Change to the site (I am attaching a screenshot showing the before and after)
• Code example added (and I also added the example to all translated languages)
• Improved translation
• Added new translation (and I also added a notice to each document missing translation)

Checklist

• I have read the contributing document.
• I have used hugo to render the site/docs locally and I am sure it works.

[diemol]

Thank you @harsha509!