Correct `until`, note on `function`, grammar fixes

Changes to %docs/red-system-specs.txt

1. Added notes about about `function` as discussed here: http://chat.stackoverflow.com/transcript/message/19351446#19351446

2. Fixed where descriptions about whether or not the condition is met in `until` were the wrong way around on 2 occasions.

3. Minor grammar fixes.

Also logged the above changes under the Document History. Was that right?