Update cell_hashing.md

Author: marypiper

scRNAseq/scRNAseq_analysis_tutorial/lessons/cell_hashing.md

@@ -98,7 +98,7 @@ Now to run the `cellranger count` command, we can include this information:
                    --libraries=library.csv \
                    --transcriptome=/n/shared_db/mm10/uk/cellranger/6.0.0/6.0.0/refdata-gex-mm10-2020-A/ \ # change for experiment
                    --feature-ref=feature_ref.csv \
-                   --expect-cells=15000 \ # change for experiment
+                   --force-cells=30000 \ # change for experiment
                    --localcores 6 \
                    --localmem 64 
   ```