* [fix] Update about section of Invidious
Another website and new documentation
* [fix] Correct engine name in for Rumble (#11)
* [fix] Wording for Filtron error message (#12)
The language_support variable is set to True by default,
and set to False in only 5 engines.
Except the documentation and the /config URL, this variable is not used.
This commit remove the variable definition in the engines, and
set value according to supported_languages length: False when the length is 0,
True otherwise.
Close#2485