gene_clustering methods (1 & 2) should be clarified in the help section

[dputhier]

Here the text indicate that a graph was previously constructed which is not the case.

#' * when 'keep_nn = FALSE', the method construct a graph only based on the previously selected genes.
#' * when 'keep_nn = TRUE', the method conserve the graph constructed using select_genes with selected genes and their nearest neighbors.
#' Then the method use the MCL algorithm to detect clusters of co-expressed genes.

[dputhier]

These methods should be renamed.
closest_neighborhood
reciprocal_neighborhood