Wrong doc

[The docs for `mixedsort`](https://cran.r-project.org/web/packages/gtools/refman/gtools.html#mixedsort), regarding the parameter `decreasing`, says:

>  logical.  Should the sort be increasing or decreasing? Note that descending=TRUE reverses the meanings of na.last and blanks.last.

But there is no `descending` parameter