Added chapter 0 of part 1. The filename is formated this way.

	[Part][Chapter]-[Title_of_chapter].md

Markdown doesn't support footnotes so I used links instead, that should
do the job.
Added a missing newline before the list.
Fixed markup of parenthesis around footnotes.
Some language fixes.
Added missing comma
Merge pull request #2 from zudov/chapter01

Chapter01