No user oriented network configuration in `microcloud init` or in a documentation

```
$ snap list microcloud lxd
Name Version Rev Tracking Publisher Notes
lxd 5.21.3-c5ae129 33110 5.21/stable canonical✓ in-cohort
microcloud 2.1.1-202e275 1781 2/stable canonical✓ in-cohort
```

We have the following step in `microcloud init` of asking what network interface should be used for MicroCloud's **internal** traffic.

```bash
$ sudo microcloud init
Waiting for services to start ...
Do you want to set up more than one cluster member? (yes/no) [default=yes]:
Select an address for MicroCloud's internal traffic:
Filter |
┌─────────────────┬─────────┐
│ ADDRESS │ IFACE │
├─────────────────┼─────────┤
✓ │ 192.168.123.232 │ enp1s0 │
│ 192.168.101.205 │ enp8s0 │
│ 192.168.102.171 │ enp9s0 │
│ 192.168.103.186 │ enp10s0 │
└─────────────────┴─────────┘
space to select; enter to confirm
↑/↓ to move; → to select all; ← to select none
```

However, there is no question about how to expose MicroCloud for **users**. In reality, it looks like the **internal** network is assumed for users to use to reach out to LXD API, MicroCloud dashboard (LXD UI) etc. That's confusing from a UX point of view. We should ask where they want to expose Microcloud on, and where to use for real internal traffic. Of course those traffic separation is optional.

There is no mention to users (web browser, LXD API client, etc.) in networking documents:
- https://documentation.ubuntu.com/microcloud/latest/microcloud/explanation/networking/
- https://documentation.ubuntu.com/microcloud/latest/microcloud/reference/requirements/