Make it more agnostic

[doitwithnotepad]

Umbrel build process will be essentially the same, but others can personalize more her builds.

RELAY_PROXY_PORT and RELAY_DATA_STORE does the evident.

When REACT_APP_OFFICIAL isn't set or set to true it shows the default <p>, when set to false it doesn't appear.

cd ./ui
npm ci
REACT_APP_OFFICIAL=false npm run build