Fixed a typo in human_defense.dm and updated an outdated message in cyborg examine.dm.
"The ironclad rule - no exceptions - is that if you can replace the word with "it is" or "it has," use it's. Otherwise, it's always its." Grammar fix for borg examine.
Merge pull request #394 from Petethegoat/typofixes2

Fixed a typo in human_defense.dm and updated an outdated message in cyborg examine.dm.