Minor fix to documentaton suggestion

Hi:

I was trimming down my embedded linux distribution and suddenly found that my Remote GDB Server configuration stopped working.   Found the issue.   If you modify the doc section below to state that you also need SFTP it will all be good.  Not all SSH implementations  include SFTP.  Once I explicitly added that to my linux build then the remote GDB server started working just fine again.

So it should say: Remote OS: Any supporting gdbserver, SSH and SFTP.

Thank you for the suggestion, we will improve the article!