naming of cell ranger index

[qiwang7]

https://bioinformatics-core-shared-training.github.io/UnivCambridge_ScRnaSeqIntro_Feb2022/UnivCambridge_ScRnaSeqIntro_Base/Markdowns/03_CellRanger.html

The created cell ranger index is called "cellranger_index". Personally, I would make it more specific as there might be more than one index in one project, e.g. Homo_sapiens_GRCh38_104_chr21_cellranger_index.

This may also help the participants to be more aware of file naming when creating their own.