[Feature]: Add documentation for the -u switch (for specifying authentication provider).

[pvillads]

Is your feature request related to a problem? Please describe.

Currently we have introduced the concept of certificates, and that is switched on by using the -u switch, However, this is not documented yet.

These are the switches for the console application:
{ "-u", "UserAuth" } - username/password or certificate or browser,etc
{ "-a", "UserAuthType"} - localcert or keyvaultcert etc

Describe the solution you'd like

These options need to be documented. Also, when the user asks for help inside the Pac cli, these options need to be mentioned.

Describe alternatives you've considered

No response

Additional context?

No response

[pvillads]

2 days of work