Add CONTRIBUTING.fr.md (#658)

* add CONTRIBUTING.fr.md

* Add language links

Co-authored-by: James Harris <wopian@wopian.me>

CONTRIBUTING.zh_tw.md

@@ -3,6 +3,7 @@
 :crossed_flags:
 [English][EN],
 [Español][ES],
+[Francais][FR],
 [Nederlands][NL],
 [Português][PT_BR],
 [Türkçe][TR],
@@ -13,6 +14,7 @@
 [AR]:CONTRIBUTING.ar.md
 [EN]:CONTRIBUTING.md
 [ES]:CONTRIBUTING.es.md
+[FR]:CONTRIBUTING.fr.md
 [KO_KR]:CONTRIBUTING.ko_kr.md
 [PT_BR]:CONTRIBUTING.pt_br.md
 [TR]:CONTRIBUTING.tr.md