docs(cli): clarify AddBranch shared settings

[fuguiKz]

Context: spectreconsole/spectre.console#661 asked for clearer AddBranch guidance; CLI docs now live in this repo.

Changes:

• Clarify AddBranch generic vs non-generic overloads on the command hierarchies page.
• Add a tip for commands without extra args (like list): give them a dedicated settings type inheriting from the branch settings.
• Update the CommandHierarchies demo app to use RemoteListSettings : RemoteSettings so shared options work consistently.

Verification:

• dotnet build Spectre.Docs.slnx -c Release
• dotnet run --project Spectre.Docs.Cli.Examples/Spectre.Docs.Cli.Examples.csproj -c Release -- 'M:Spectre.Docs.Cli.Examples.DemoApps.CommandHierarchies.Demo.RunAsync(System.String[])' remote --verbose list

[fuguiKz]

FYI the GitHub Actions check suite is currently in an "action required" state (fork workflow approval), so CI hasn't run yet.

Could a maintainer approve and run the workflows for this PR? I ran dotnet build Spectre.Docs.slnx -c Release locally as a quick sanity check.

[phil-scott-78]

sorry for the delay getting to this, was out traveling for the holidays. Looks good, thanks for taking the time to improve the docs