add optional prefix to extract title

bin/extract_title.sh

@@ -2,6 +2,7 @@
 # extract title of research topic
 
 filename=$(basename -- "$1")
+prefix=$2
 
-echo "## `head -n 1 $1 | sed -e "s;#\s*;\[;g" -e "s;\(.*\);\1\](${filename%.md}.html);g"`"
+echo "## `head -n 1 $1 | sed -e "s;#\s*;\[;g" -e "s;\(.*\);\1\]($prefix${filename%.md}.html);g"`"