docs: Customize Azure resources has inaccurate docs

[kamranayub]

The docs for customizing Azure resources seems to be outdated/incorrect in a bunch of places (hallucinated? 🥲 ):

• AddAzureBicepResource doesn't exist, it's AddBicepTemplate and AddBicepTemplateString
• Generated Bicep files don't exist in the AppHost directory, especially not under infra
• @davidfowl mentioned PrivateEndpoint might be made up too -- there could be others

To share some more context, I would love if these docs also showed:

• How to pass ParameterResources and other kinds of parameters (like referencing another resource expression)
• How to get the output from the Bicep resource to use elsewhere in the AppHost
• How to get "resource IDs" or other outputs from other Azure resources to pass in as parameters
• How to handle existing in the Bicep file

The samples do show most of this, so that's what I referenced (but this isn't linked from the docs, either):

https://github.com/dotnet/aspire/tree/main/playground/bicep