Improve the description of `peaksPerCell` in the `addReproduciblePeakSet` function

[ycl6]

The description of the peaksPerCell param in the addReproduciblePeakSet function (for peak calling) is a bit misleading.

ArchR/R/ReproduciblePeakSet.R

Lines 16 to 18 in 2109b3a

	#' @param peaksPerCell The upper limit of the number of peaks that can be identified per cell-grouping in `groupBy`. This is useful
	#' for controlling how many peaks can be called from cell groups with low cell numbers.
	#' @param maxPeaks A numeric threshold for the maximum peaks to retain per group from `groupBy` in the union reproducible peak set.

Although the maintainer has answered what this param is GreenleafLab/ArchR#1082, but looking at the code, the peaksPerCell is still not a threshold to limit the number of peaks per cells, rather used to calculate maxPeaks for a cell group.

ArchR/R/ReproduciblePeakSet.R

Lines 160 to 168 in 2109b3a

	data.frame(
	Group=names(coverageParams$cellGroups)[y],
	nCells=tableGroups[names(coverageParams$cellGroups)[y]],
	nCellsUsed=length(uniq),
	nReplicates=length(x),
	nMin=nmin,
	nMax=nmax,
	maxPeaks = min(maxPeaks, length(uniq) * peaksPerCell)
	)