fix(README-FR): fix typos, grammar and translation errors

[Robocnop]

Description

Describe the changes
Fixed multiple typos, grammar mistakes and translation errors in the French README.

What is the current behavior?
The French README contained several errors: missing verb, duplicate word, missing articles, wrong translation of "inherits from", missing accents, grammatical errors and typos in code comments.

What is the new behavior?
N/A

Does this PR introduce a breaking change?
No.

Other information:
N/A

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentations

Submission checklist

• I have checked the project can be compiled
• I have tested my changes and it worked as expected

Patches (if there are any changes related to Harmony patches)

• I have checked no IL patching errors in the console

Other

• Still requires more testing