#LOF introducing otherguides text variable and stable fr markdown posts

- FR links updated, they now lead to /fr/intermediate and /fr/advanced.
- Markdown post for intermediate and advanced were added and outputted at /fr/intermediate and /fr/advanced.
- Introduced a new variable: The second navigation bloc always uses the label "Others guides". We introduced a new variable in post files level. The nav bloc will use "Others guides" by default or the label defined in this var for each lang/post
- New FR screenshots added