Added section to top of script, briefly describing what it does and how it works

build.sh

@@ -3,6 +3,27 @@
 # TODO: Add a comment block at the top of the script, describing what it does.
 # TODO: Add a '-h' or '--help' flag, that displays information about the script, and how to use it.
 
+
+#  sitegen / s4g
+#  -------------
+#
+#  This is a static-site generator, that can be used to convert Markdown files into HTML.
+#  It is extremely simple and extremely opinionated, as you can see if you read the code below.
+#  A lot of paths and directories are hard-coded, to suit my workflow.
+#
+#  To use it, create a directory for your project (e.g. 'website'). Inside 'website', create
+#  two directories: 'source' (which holds your Markdown files) and 'output' (which holds the
+#  converted CSS.
+#
+#  In addition to these directories, three files are needed in 'website':
+#  1. 'header.html' - A header, which is prepended to every source file. Unfortunately, this must
+#		      be written in regular HTML.
+#  2. 'footer.html' - A footer, which is appended to every source file. Also must be written in HTML.
+#  3. 'styles.css' - A global stylesheet.
+#
+# If you have any comments or questions, please email aadhavan@twomorecents.org.
+
+
 set -o errexit # Stop executing when a command fails
 set -o nounset # Stop executing when accessing an unset variable
 set -o pipefail # Treat a pipeline as failing, even if one command in the pipeline fails