Bootstrap, State Replica, and Gateway patterns missing examples.

[maclema]

The Gateway Pattern page has 'tbd' placeholder under the example box.

[maclema]

Bootstrap, State Replica, and Gateway patterns missing examples.

[pabloariasmora]

Adding References:

• Device Bootstrap: https://iotatlas.net/en/patterns/device_bootstrap/#example
• State Replica: https://iotatlas.net/en/patterns/device_state_replica/#example
• Gateway: https://iotatlas.net/en/patterns/gateway/#example