Fix typo in "RefTests" -- use lowercase "t"

Fix typo: use lowercase "t" in "Reftests" (not "RefTests")

The correct spelling (with lowercase "t") can be seen on the target-page itself, at http://testthewebforward.org/docs/reftests.html
Merge pull request #1 from dholbert/patch-1

Fix typo in "RefTests" -- use lowercase "t"