Use matrix.to links instead of chat.mozilla.org ones

[thibaultamartin]

This allows people using a desktop client or their own instance to be able to join the conversation easily. If the person who clicks on the link doesn't use Matrix, they will be redirected to Mozilla's Matrix instance (chat.mozilla.org)

[JRMeyer]

you might check out: https://github.com/mozilla/DeepSpeech/issues/3693