Document allowed values for BAR subscriptions

I was following https://github.com/dotnet/arcade/blob/master/Documentation/DependencyFlowOnboarding.md, which provides some sample values for configuring BAR subscriptions. Where can I find more details on allowable settings?

For instance, the docs show this:

Channel: .NET Tools - Latest
# ...
Merge Policies:
- Name: AllChecksSuccessful
  Properties:
    ignoreChecks:
    - WIP
    - license/cla

Questions:

• The interactive prompt shows two suggested channels. Where can I see a list of all available channels?
• What other merge policies are available?
• What other properties are allowed AllChecksSuccessful merge policy?
• How do the merge policies apply to PRs made in Azure Repos?

FWIW - I see some of this is documented in code (https://github.com/dotnet/arcade/blob/master/src/Microsoft.DotNet.Darc/src/Darc/Models/PopUps/AddSubscriptionPopUp.cs), but it only appears if you run add-subscription in interactive mode. Would be nice to make this content available in documentation without having to execute a command which modifies subscription state.

[jcagme]

I can take a stab while you get gather-drop sorted

[jcagme]

This is done