Distributed Example Runtime Error

[MarkintoshZ]

Running cargo run --example distributed gives the following error

thread 'main' panicked at 'index out of bounds: the len is 0 but the index is 0', examples/distributed.rs:28:50
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
[2022-07-23T18:19:31Z WARN  lunatic_process] Process 1 failed, notifying: 0 links
    			    (Set ENV variable `RUST_LOG=lunatic=debug` to show stacktrace)

[withtypes]

The example assumes at least two nodes. I will fix the example, but I also have to check something when those distributed spawns are called on non-distributed lunatic.

[MarkintoshZ]

It looks like the code is fixed! But I think we should add some docs so people know how to run this example.