Add more detailed info about the differences between private group and forum
One important aspect of Briar is that apparently in a private group all communication flow goes through the creator's device, which can significantly delay communication.
Example: If a group has three members (Alice, Bob, Creator) the following appears to be the case: Alice posts a message to the group. The message is sent from Alice's device to Creator's device only when the devices are within Wifi or Bluetooth range or simultaneously have contact to the internet. The message is then forwarded from Creator's device to Bob's device only when these two devices are within Wifi or bluetooth range or simultaneously have contact to the internet. If Creator is out of range or away from the internet for an extended time, communication between Alice and Bob is not possible and they will be confused why their messages don't arrive.
Forums are "faster", as messages can also be exchanged between forum members' devices without going through Creator's device.
This info should be available in the manual.
Of course, communication delay of both private groups and forums will likely be reduced in the future if the mailbox function is used.