04_Preprocessing_And_QC.Exercise.html with one more viewing of data line

[qiwang7]

https://bioinformatics-core-shared-training.github.io/UnivCambridge_ScRnaSeqIntro_Feb2022/UnivCambridge_ScRnaSeqIntro_Base/Markdowns/04_Preprocessing_And_QC.Exercise.html

At the end of 7(Add per cell QC metrics), before 8 (Explore QC metric distribution), we may consider adding a line:

head(colData(sce))

so the student can see themselves that additional column have been added to sce column data. This addition may help to create a more smooth transition to the next plotting step.

That line was in https://bioinformatics-core-shared-training.github.io/UnivCambridge_ScRnaSeqIntro_Feb2022/UnivCambridge_ScRnaSeqIntro_Base/Markdowns/04_Preprocessing_And_QC.html