[Rd] Minor: bad label in "faithful" dataset (PR#8485)

[greg.kochanski@phon.ox.ac.uk]

Full_Name: Greg Kochanski
Version: 2.2.0
OS: Debian Linux i686
Submission from: (NULL) (212.159.16.190)


The data set for "faithful" appears to be (column 1) the duration
of the eruptions, and (column 2) the interval between eruptions.
(See http://stat.ethz.ch/R-manual/R-patched/library/datasets/html/faithful.html).

The label of column 1 is wrong, and should be "eruption duration"
not just "eruptions", which implies a count of eruptions not a duration.