expanding proposed "documentation" property

Hi All,

I've been taking a look at the new "documentation" property being proposed
here (http://pending.schema.org/documentation). I suggest that the domain
be expanded to include http://schema.org/Product - allowing for describing
things such as owner manuals, assembly instructions, and manufacturer spec
sheets.

I've added a note in the related issue around WebAPIs (
https://github.com/schemaorg/schemaorg/issues/1423), and would be
interested to hear if others see the usefulness in this expansion.

Cheers,
--Eric

-- 
*Eric Axel Franzon*