Merge pull request #3 from lcolladotor/master

Fixed typos, added links
added section on encoding information with formatting instead of text (bad!!)
update NR contribution.
Merge pull request #5 from nickreich/master

Added section on proper encoding of variables in Excel.
Update README.md

typo
Fixed links ending in )
Merge pull request #7 from jimktrains/master

Fixed links ending in )
Merge pull request #6 from snoldak924/patch-1

Update README.md
Update README.md

Change stated number of "general principles" in the "tidy data set" section from "three" to "four".
Merge pull request #8 from rpglover64/patch-1

Update README.md
fix typo
Merge pull request #9 from nikai3d/patch-1

fix typo