Add how-to guide to retrieve OSM usernames and passwords

Once the installation is over, follow these instructions to use the osmclient:

```bash

NBI_IP=juju status --format yaml | yq r - applications.nbi-k8s.address

NBI_IP=$(microk8s.kubectl describe -n osm ingress | grep -E "nbi.*\.io" | xargs)

export OSM_HOSTNAME=$NBI_IP

NBI_PASSWORD=$(juju config -m osm keystone admin-password)

export OSM_PASSWORD=$NBI_PASSWORD

```

To have the osm client always available include it in your `.bashrc`:

```bash

NBI_IP=juju status --format yaml | yq r - applications.nbi-k8s.address

NBI_IP=$(microk8s.kubectl describe -n osm ingress | grep -E "nbi.*\.io" | xargs)

echo "export OSM_HOSTNAME=$NBI_IP" >> ~/.bashrc

NBI_PASSWORD=$(juju config -m osm keystone admin-password)

echo "export OSM_PASSWORD=$NBI_PASSWORD" >> ~/.bashrc

```

#### How to retrieve login usernames and passwords in OSM Charmed installations

The following instructions show how to retrieve usernames and passwords of OSM modules in Charmed installations.

##### OSM UI

The following commands return the username and password for logging into OSM UI as administrator:

```bash

juju config -m osm keystone admin-username

juju config -m osm keystone admin-password

```

If you also need the exposed IP address for the UI, you can issue the following command:

```bash

microk8s.kubectl describe -n osm ingress | grep -E "ui.*\.io" | xargs

```

##### Grafana

The following commands return the username and password for logging into Grafana dashboard:

```bash

juju config -m osm mon grafana-user

juju config -m osm mon grafana-password

```

##### Prometheus

The following commands return the username and password for logging into Prometheus dashboard:

```bash

juju config -m osm prometheus web_config_username

juju config -m osm prometheus web_config_password

```

##### Databases

**Disclaimer**: manual access to the databases is usually not required and we strongly suggest not to perform operations on them. However, in case the is a particular reason to access and/or manually modify them, here you can find the steps to retrieve the login data for Keystone and MariaDB.

###### Keystone

The following commands return the username and password for logging into Keystone:

```bash

juju config -m osm keystone admin-username

juju config -m osm keystone admin-password

juju config -m osm keystone keystone-db-password

juju config -m osm keystone service-password

 ```

###### MariaDB

The following commands return the username and password for logging into MariaDB:

```bash

juju config -m osm mariadb root_password

juju config -m osm mariadb password

```

#### Scaling OSM Components