add comments describing relative directory change

code/pcgen.sh

@@ -1,5 +1,9 @@
 #!/bin/sh
 set -e
+
+# Changing the current directory temporarily to the file location.
+# Ensuring the script operates relative to its own location, regardless
+# of where it is run from
 cd "$(dirname "$0")"
 
 # Most GUIs will change directory to the location of the script