Add a better intro blurb, and link in the learner profiles.

This partially fixes #15, but we still need instructor notes.

index.md

@@ -4,19 +4,34 @@ root: .  # Is the only page that doesn't follow the pattern /:path/index.html
 permalink: index.html  # Is the only page that doesn't follow the pattern /:path/index.html
 ---
 
-A lesson introducing the Snakemake workflow system for bioinformatics analysis.
+A lesson introducing the [Snakemake workflow system](https://snakemake.github.io/) for bioinformatics
+analysis. The Snakemake system enables the writing of reliable, scalable and reproducible scientific
+workflows as a series of chained rules. Simple workflows to replace shell scripts can be written in a
+few lines of code, while for more complex cases there is support for conda integration, software containers,
+cluster execution, cloud execution, etc. You can also add Python and R code directly into your workflow.
+
+This lesson introduces the core concepts of Snakemake in the context of a typical analysis task, aligning
+short cDNA reads to a reference transcriptome. Later episodes focus on practical questions of workflow design,
+debugging and configuration.
+
+We also look at the Conda integration feature of Snakemake, with which you can author reproducible
+and shareable workflows with a fully-specified software environment.
+
+In the planning phase of writing this course material we outlined some [learner profiles](learner_profiles/),
+to expand on who we think will benefit from this lesson and why.
 
 <!-- this is an html comment -->
 
 {% comment %} This is a comment in Liquid {% endcomment %}
 
 > ## Prerequisites
 >
-> This is an intermediate lesson and assumes learners have already done some bioinformatics:
-> * Familiarity with the BASH command shell, including concepts like pipes, variables and loops.
-> * Knowledge of bioinformatics fundamentals like the FASTQ file format and transcriptome sequencing, in order to understand the example workflow.
+> This is an intermediate lesson and assumes learners have some prior experience in bioinformatics:
+> * Familiarity with the Bash command shell, including concepts like pipes, variables and loops.
+> * Knowledge of bioinformatics fundamentals like the FASTQ file format and transcriptome sequencing,
+>   in order to understand the example workflow.
 >
-> No previous knowledge of Snakemake or workflow systems is required.
+> No previous knowledge of Snakemake or workflow systems, or Python programming, is required.
 {: .prereq}
 
 {% include links.md %}

setup.md

@@ -35,7 +35,7 @@ GEdit is the text editor that comes with the GNOME desktop and is a great genera
 menus it is normally just called "Text Editor" but you can also start it from the shell by typing "gedit &".
 
 Snakemake uses Python file structure which is very fussy about editor settings, particularly the use of Tab characters.
-Before using GEdit, you need to go into the preferences and select the following settings:
+Before writing any code in GEdit, you need to go into the preferences and select the following settings:
 
 * Insert spaces instead of tabs (under the "Editor" tab)
 * Disable text wrapping (under the "View" tab)