Add "Redirect both stdout and stderr of child process to the same fle"

[ludwigpacifici]

fixes #345

[ludwigpacifici]

Hello @budziq

I change the command from find / (what I suggested in #345) tols. The execution time is quicker.

Also, I hardcoded the filename. I saw a crate to create temporaries, but the example would be less minimal.

Let me know your thoughts.

[budziq]

Nice! Just some minor suggestions below.

[budziq]

Nice! Just some minor suggestions below.

[budziq]

The api itself is cross platform so I would avoid mentioning unix here. Would rather go with child processes.

[budziq]

Here we can mention that the example would be equivalent to following Unix shell command.

[budziq]

the statement might be slightly misleading. we might want to rewrite to emphasize that process::Stdio will write to provided Fileand that File::try_clone will duplicate the file handle ensuring the write pointer is synchronized for stderr and stdout

[ludwigpacifici]

@budziq, PR updated with your comments.

I also changed changed the equivalent Unix command from ls . oops &> out.txt to
ls . oops >out.txt 2>&1. The former may not be compatible and the later is more standard.

[budziq]

Well done!

[ludwigpacifici]

Thanks!