notedeck : allow relay pool customization via -r/--relay argument
This allows you to use specific relays instead of some random
bootstrap ones we are currently using
Fixes: https://github.com/damus-io/notedeck/issues/154
Changelog-Added: Add -r/--relay cli option for customized relay pool
Signed-off-by: William Casarin
https://github.com/damus-io/notedeck/commit/f2c5978ba5df8719af0f7a115033d97d6a31caf7