Merge branch 'master' of gitlab.svi.edu.au:biocellgen-public/svi-sahmri_scrna-seq-workshop_2021-july

Jeffrey edits take 2

See merge request !2

Filled in:

* Doublet detection
* Gene filtering
* Exploratory data analysis
* Matrix factorization and latent spaces

I removed the Autoencoders section as we don't have a good example and
because of time constraints.

Edits from Jeffrey

See merge request !1