Reference more complete and up-to-date architecture document

The document referenced by the "Anatomy of a Database System" title is
available as a complete and apparently final version at a different url.

The document currently linked is not complete.
README.md Typo fix externel -> external
Merge pull request #6 from dragansah/master

README.md Typo fix externel -> external
README.md External Reading Lists MIT 2014 and 2010
Change CAP article link

This is the original article from the IEEE 'Computer' journal. Also interesting is this [paper](http://informatik.unibas.ch/fileadmin/Lectures/HS2012/CS341/workshops/reportsAndSlides/ReportKevinUrban.pdf) and [slides](http://informatik.unibas.ch/fileadmin/Lectures/HS2012/CS341/workshops/reportsAndSlides/PresentationKevinUrban.pdf) by Kevin Urban discussing the article.
Merge pull request #11 from dragansah/master

README.md External Reading Lists MIT 2014 and 2010
Merge pull request #5 from oseemann/master

Reference more complete and up-to-date architecture document
Added more stuff about AlphaSort.
Merge pull request #12 from grkvlt/patch-1

Change CAP article link to original article from IEEE Computer journal
Merge pull request #1 from rxin/master

Update list from master list.