Changed 'and' to 'an'; added 'to' for better reading.
Changed 'article' to 'chapter' for consistency with other pages.
Altered muddy 'how' phrase; added 's'; clarified what 'non-browser' might mean.
Changed to possessive apostrophe.
Clarified iframe origin; also common example with word additions, like 'API'.
Removed sentence fragment and unneeded 'the'.
Merge pull request #14 from Steve-A-Orr/master

LIttle copy changes for readability