Fixed minor syntax issues in Chapter 6

Role-Based Access Control (RBAC) is available in OSM to bring different users and projects a controlled access to resources. Authorization is granted if a user has the necessary role to perform an action.

For achieving this, two backends are available:

- Internal (default): handles identity and assignment resources locally by NBI.

- Keystone: external component to handle identity and assignment resources, together with out-of-the-box integrations (i.e. LDAP) and more advanced use RBAC cases.

That means that, in order to obtain privileges to do something in OSM, you should have a user, belonging to a project, with a specific role over the project.

By default, OSM starts with the following credentials:

- User: admin

- Project assigned to user: admin

- Role assigned to user: system-admin (system-wide privileges)

  osm-project-update             updates a project (only the name can be updated)

```

Most of the commands are intuitive, but options can be checked by using '--help'. For example:

Most of the commands are intuitive, but options can be checked by using `--help`. For example:

```bash

osm project-update --help

  --name TEXT  new name for the project

  -h, --help   Show this message and exit.

```

## VIM management

TODO: Page in elaboration.

OSM can handle Physical Network Functions through managing the lifecycle, in particular Day-1/2 configurations, for the Physical Deployments Units (PDUs) that are part of a given PNF.

Some relevant concepts are:

- PNF: Physical network function. It refers to a HW box that provides a networking function. For example: Routers, firewalls and load balancers.

- PDU: Physical deployment unit. It refers to the instance of the PNF that will be managed.

- HNF: Hybrid network function: Network function composed of both physical and virtual elements.