Update pathway analysis and RNA-seq cheatsheets

[jaclyn-taroni]

Closes #782

I am updating the pathway analysis cheatsheet:

• Adding setdiff()
• Removing the TODO for msigdbr()
• Commenting out the DESeq2 section -- let me know if you think it should get completely removed
• Small change to description of gsvaParams()

But I also realized the heatmap material wasn't fully covered by the RNA-seq cheatsheet:

• Removing pheatmap and adding a ComplexHeatmap table
• Adding documentation for some of the matrix statistics functions (base R & matrixStats)

[jashapiro]

This looks good to me. I still have to add EnhancedVolcano to this, which I think I will add in the same table as ComplexHeatMap?

[jaclyn-taroni]

I still have to add EnhancedVolcano to this, which I think I will add in the same table as ComplexHeatMap?

That seems very reasonable to me!