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

url parser gets confused because "(" and ")" and "-" are valid url characters so outside of removing one level of balanced parentheses, additional ones are parsed to be part of a valid url.

This can be resolved by adding a space (1st and 3rd example) or just removing the extra set of parenthesis (2nd example).