markdown formatting to make url parsing easier

BAD : (http://www.jsoftware.com/books/pdf/calculus.pdf)(PDF)
GOOD: (http://www.jsoftware.com/books/pdf/calculus.pdf) (PDF)

BAD : ([PDF](http://www.kamishima.net/archive/mlmpyja.pdf), [EPUB](http://www.kamishima.net/archive/mlmpyja.epub))- 神嶌敏弘
GOOD: [PDF](http://www.kamishima.net/archive/mlmpyja.pdf), [EPUB](http://www.kamishima.net/archive/mlmpyja.epub) - 神嶌敏弘

BAD : (http://introcs.cs.princeton.edu/java/home/)- Robert
GOOD: (http://introcs.cs.princeton.edu/java/home/) - Robert
Merge pull request #764 from borgified/url_fixes_easier_parsing

markdown formatting to make url parsing easier