Update docs for federated identity credentials

[wbreza]

Update docs for new OIDC (federated identity credentials)

Pipeline Config: https://learn.microsoft.com/en-us/azure/developer/azure-developer-cli/configure-devops-pipeline?tabs=GitHub
FAQ: https://learn.microsoft.com/en-us/azure/developer/azure-developer-cli/faq

Related: #408

Details for feature documented: #1086

[puicchan]

@hhunter-ms, can you take a look?

[puicchan]

Done