Add new subcommand list

Also add it to the readme and manpage.

src/main.rs

@@ -7,6 +7,7 @@ mod posix;
 enum Command {
     Create(posix::Create),
     Info(posix::Info),
+    List(posix::List),
     Unlink(posix::Unlink),
     Send(posix::Send),
     Recv(posix::Recv),
@@ -47,6 +48,7 @@ fn main() -> Result<()> {
         Command::Unlink(u) => u.run()?,
         Command::Send(s) => s.run()?,
         Command::Recv(r) => r.run()?,
+        Command::List(l) => l.run()?,
     }
 
     Ok(())