Restore config.json section for old Riot
Restore config.json section for old Riot

Riot includes a link to the config.json section of the README, so let's restore
it (at least for a while) keep that link working.

vector-im/vector-web,vector-im/riot-web,vector-im/riot-web,vector-im/vector-web,vector-im/riot-web,vector-im/vector-web,vector-im/vector-web,vector-im/vector-web,vector-im/riot-web,vector-im/riot-web,vector-im/riot-web