Document expected behavior of `LeaderElector.RunAsync()`

[PSanetra]

Describe the bug
LeaderElector.RunAsync() is not documented at the moment, but it seems like RunAsync() will only try once to obtain a Lease and will just exit after loosing leadership (e.g. during network issues). This behavior might be unexpected as the bug in dotnet/dotnet-operator-sdk#677 is showing and should be documented to avoid confusion.

Kubernetes C# SDK Client Version
12.1.1

Server Kubernetes Version
v1.27.3

Dotnet Runtime Version
net7

[tg123]

could you please send pr to add doc?

[PSanetra]

@tg123 Done 🙂