French translation for the readme.md file

[m1-gl]

Proposal of a french translation for the readme.md file. This translation can be accessed by a link in the original file to a new file named readme.fr.md.

[luolong]

@FroMage Maybe you can review this french translation!

[danielleberre]

Fixed a few typos.

[davidfestal]

I submitted a few fixes as suggestions.
If you could accept suggestions proposed by @danielleberre it would be great.

Last point: After accepting the suggestions, could you please rebase your PR with signed commits. Your email address used in the commit should be the one used in your Eclipse Contributor Agreement (ECA). If you never signed an Eclipse ECA, just have a look here for more information: https://www.eclipse.org/legal/ECA.php and proceed with ECA here: https://accounts.eclipse.org/user/eca

It should be quite straightforward.

[m1-gl]

I accepted every suggestion and signed the eclipse ECA. I also changed my github settings to set the same mail address used in my eclipse account as my public email instead of the mail address set by default but it does not change on the "re-validate" page, it still shows the automatically attributed mail github ending in .noreply

@davidfestal mentioned a PR rebase, I have been searching how to do it but have been unsuccessful so far. How should I proceed ?

[Kevin-DDR]

All those changes seem pertinent

[Voiteh]

@m1-gl I guess You need to sign-off all commits. I would close this pull request, reset all changes, commit it again with sign-off and pull request again. I don't any know better approach.