Update main pblog script to create OUTPUT directory if it does no yet exist

pblog.sh

@@ -6,6 +6,10 @@ source _config.sh
 # !WARNING!
 # You probably don't need to tweak anything below this line. Edit at your own risk!
 ###################################################################################
+
+# Create the $OUTPUT directory if it does not exist yet
+mkdir -p $OUTPUT
+
 if [[ $TOC = true ]]
   then
     TOC_TOGGLE="--toc";