Tiny typo.
Fixed small typo

Fixed a small typo that I noticed in the design docs.
Pretty sure it was meant to say "turned off" instead
of "turned of".
Add a note about getting help through man pages
Merge branch 'zanchey-docs'

Conflicts:
	doc_src/index.hdr.in
Clarify "input/output methods" in documentation
Manually cleaned up Mercurial completions.
Add completions for cabal; closes #567
Added documentation for printf

Fix for https://github.com/fish-shell/fish-shell/issues/488
Avoid generating man page and help section for printf (to fallback on system man page for printf)
Formatting and style updates
Typos in the fish OS X package installer rtf file
update cvs completions
update darcs completions