Add French podcasts (#6171)

* Add French podcasts

* Fix error in markdown

* Remove trailing slash

* Add blank line between last setion and next heading

* Add blank line between last setion and next heading

* Update README.md

casts/free-podcasts-screencasts-fr.md

@@ -0,0 +1,19 @@
+### Index
+
+* [Java](#java)
+* [Langage Agnostique](#language-agnostic)
+
+
+### Java
+
+* [Les Cast Codeurs Podcast](https://lescastcodeurs.com) (podcast)
+
+
+### Language Agnostic
+
+* [Artisan Developpeur](https://artisandeveloppeur.fr/podcast) (podcast)
+* [Dev'Obs](https://devobs.p7t.tech) (podcast)
+* [IFTTD - If This Then Dev](https://ifttd.io) (podcast)
+* [Le Comptoir Sécu](https://www.comptoirsecu.fr) (podcast)
+* [Message à caractère informatique](https://www.clever-cloud.com/fr/podcast) (podcast)
+* [NoLimitSecu](https://www.nolimitsecu.fr) (podcast)