Resolve "refactor vars"

Closes #2 (closed) #9 (closed)

• I have changed TheRojam variables to E-lie variables because, as said, the latter were more flexible and consistent with Ansible good practises.
• I have tested the changes and the role still works perfectly.
• Readme in English / French with variables changes (suggestions for evolution are welcome!).

default/main.yml

@@ -6,7 +6,7 @@ ynh_admin_password: MYINSECUREPWD_PLZ_OVERRIDE_THIS
 
 # The list of Yunohost domains.
 ynh_main_domain: domain.tld
-ynh_extra_domains: ~
+ynh_extra_domains: null
 ynh_ignore_dyndns_server: False
 
 # The list of Yunohost users.
@@ -23,4 +23,4 @@ ynh_apps: null
   #   link: ttrss # It can be the name of an official ynh app or a git repo link
   #   args: # Provide args here. Domain and path are mandatory, other args depend on the app (cf manifest.json of app).
   #     domain: domain.tld
-  #     path: /ttrss
\ No newline at end of file
+  #     path: /ttrss