[Rd] Improvement in hist command documentation

[Jérôme LAURENS]

Hi all,

In the histogram created with the `hist` command, the label of the y axis reads "Frequency ».
Finding that the ylab key is used to change (localize) that word may seem difficult for people
who are beginners either in R or in english.

I suggest very minor modifications of the file hist.Rd at https://svn.r-project.org/R/trunk/src/library/graphics/man/hist.Rd.
1) make the default value for ylab explicit, similarly to main and xlab
2) make the word "label" explicitly appear in the documentation for the ylab key

That way, people looking either for the word "label" or the word "Frequency" in hist’s help will get more chance to find the ylab key.

Here is the diff with revision 77240

17c17
<      xlab = xname, ylab,
---
>      xlab = xname, ylab = "Frequency",
65,66c65,66
<   \item{main, xlab, ylab}{these arguments to \code{title} have useful
<     defaults here.}
---
>   \item{main, xlab, ylab}{to change the default value of the main title,
>     the label of the x axis or the label of the y axis.}

Thanks for your efforts.

JL