Enhance demo6 README file

```sh

Mandatory commands:

        l: Login, L: Logout, s: Get scenarios list

        a <index>: Activate a scenario, d <index>: Terminate a scenario

        l: Login, n: Get Namespace, L: Logout, s: Get scenarios list

        a <index>: Activate a scenario, A: Terminate a scenario

Optional commands:

        S <index>: Get scenario description

        m: Get MEC services list

        i: Get application instances list, c: Create a new application instance, D: Delete a new application instance

        m: Get MEC application services list

        i: Get application instances list, c: Create a new application instance, C: Delete a new application instance

        u: Get UEs, x <index>: Increase UE, X <index>: Decrease UE

MEC 011 App Support:

        y: Send ConfirmReady, r: Send Registration, R: Send Deregistration

MEC 011 Service Management:

        v: Create new service, V: Delete service, g: Get list of MEC services

MEC 030:

        u: Get V2X UU unicast setting

        Y: Get V2X UU unicast setting', z: V2X Msg subscription, Z <subID>: Delete V2X subscription

MEC 040:

        0: Get Federation Systems list', 1 <systemId>: Get Federation Services list, 2 <systemId> <serviceId>: Get Federation Service, 3: Subscribe, 4 [<subId>]: Get subscription, 5 <subId>: Delete subscription

        Q: Current status:

q: Quit

Enter your choice:

```

This option (c) creates the a new USER MEC application. The application instance id is generated automatically and its name is "demo6".

This new application is attached to "mep1".

Note: Additional new application instances can be created to simulate several MEC application. This demo application is limited to one new USER MEC application.

### Delete a new application instance

This option (D) terminates an existing MEC application.

This option (C) terminates an existing MEC application.

## MEC Services commands

Theses commands provides some example of access to the MEC services available with the activated network scenario.

### Get V2X UU unicast setting

### MEC Application Support (MEC 011 service)

- The option (y) sends a confirm-ready to the MEC platform to indicate a READY state.

- The option (r) registers the MEC application to the MEC platform (optional).

- The option (Rr) de-registers the MEC application from the MEC platform (optional).

### MEC Service Managenment (MEC 011 service)

### Get V2X UU unicast setting (MEC 030 service)

- The option (Y) retrieves the UU Unicast settings from the MEC 030 service. To use it, the V2X network scenarion shall be activated (see [Activate a network scenario](#activate_a_network_scenario)).

- The option (z) creates a subscription on V2X messages.

- The option (Z) deletes a subscription.

## Application status

The option (Q) provides the demo6 application status. If a Login commands was executed, the termination process does the logout.

```

Current status: Sandbox: sbxqvgq4q4, appsInfo.Id: d75d8536-cf94-45a6-91a3-fc5b033f9630, Subscription: sub-wwJ_uzHOwqPntaia, Demo6 app not registered

```

This option (u) retrieve the UU Unicast settings from the MEC 030 service. To use it, the V2X network scenarion shall be activated (see [Activate a network scenario](#activate_a_network_scenario)).

In the example above, the MEC Platfor identifier is sbxqvgq4q4, the MEC application identifier is d75d8536-cf94-45a6-91a3-fc5b033f9630 and a subscription to the applicationTerminationNotifcation was created: sub-wwJ_uzHOwqPntaia. Note that the MEC application is not registered to the MEC Platform.

## Terminate the demo6 application

The command Quit (q) terminates the demo6 application. If a Login commands was executed, the termination process does the logout.

The command Quit (q) terminates the demo6 application. If a Login commands was executed, the termination process does the logout, deletes all subscriptions and de-registers the MEC appliction is a register was done.