Create RNA-seq readme file. (#150)

* Create RNA-seq readme file.

* alevin -> salmon

* Update README.md

* lower case all the things

* sentence case

* fix DE case

RNA-seq/README.md

@@ -0,0 +1,12 @@
+# RNA-Seq Training Module
+
+This CCDL-designed module covers the analysis of RNA-seq data using Salmon.
+It is designed to be taught in approximately 3.5 hours.
+It depends on knowledge gained in the [intro to R](https://github.com/AlexsLemonade/training-modules/tree/master/intro-to-R-tidyverse) module and analyses are performed within a [Docker container](https://github.com/AlexsLemonade/training-modules/tree/master/docker-install).
+It covers quality control steps, gene expression abundance estimation, and certain downstream analyses.
+The notebooks that comprise this module are:
+* [Quality control, trim, and quantification with salmon](https://github.com/AlexsLemonade/training-modules/blob/master/RNA-seq/01-qc_trim_quant.md)
+* [Gene-level summaries with tximport](https://alexslemonade.github.io/training-modules/RNA-seq/02-gastric_cancer_tximport.nb.html)
+* [Exploratory analyses](https://alexslemonade.github.io/training-modules/RNA-seq/03-gastric_cancer_exploratory.nb.html)
+* Differential expression analysis: [tximport](https://github.com/AlexsLemonade/training-modules/blob/master/RNA-seq/04-nb_cell_line_tximport.md) and [differential expression](https://alexslemonade.github.io/training-modules/RNA-seq/05-nb_cell_line_DESeq2.nb.html)
+* [Additional exercises](https://github.com/AlexsLemonade/training-modules/blob/master/RNA-seq/06-bulk_rnaseq_exercise.Rmd)