https://github.com/vector-im/element-web/tree/develop/docs
https://github.com/vector-im/element-web/blob/develop/docs/config.md
    https://develop.element.io/config.json
https://github.com/vector-im/element-web/blob/develop/docs/labs.md
https://github.com/vector-im/element-web/blob/develop/docs/feature-flags.md
https://github.com/vector-im/element-web/blob/develop/docs/app-load.md
https://github.com/vector-im/element-web/blob/develop/docs/customisations.md
https://github.com/vector-im/element-web/blob/develop/docs/kubernetes.md
https://github.com/vector-im/element-desktop#user-specified-configjson
    $XDG_CONFIG_HOME\$NAME\config.json or ~/.config/$NAME/config.json on Linux
https://github.com/vector-im/element-web/blob/develop/docs/config.md