Fix copypasta in README.md

I think someone might have accidentally copypasta'd the text under Windows Impersonation Example. :P
AIX returns Errno::EPERM here
Merge pull request #51 from kanerogers/patch-1

Fix copypasta in README.md
Merge pull request #52 from opscode/lcg/aix-eperm

AIX returns Errno::EPERM here
Support separate live stream for stderr
Simplify live_stream vs live_stdout vs live_stderr based on PR comments