Add a section for official standards; add POSIX.

Under the Language Agnostic section, I've added a heading for standards documents, and started by adding the POSIX standard, which links to some instructions I've posted on how to access it without paying. I actually have a number of these, if you think it's the type of thing that would be useful on this list?
Corrected typo in index
Created initial Hungarian list
Merge pull request #550 from vicziani/hungarian

Created initial Hungarian list
Merge pull request #551 from vicziani/typos

Corrected typo in index
Merge pull request #549 from g-nix/patch-1

Add a section for official standards; add POSIX.
Added Just Enough Ruby to Get By
Merge pull request #552 from serv/master

Added Just Enough Ruby to Get By