Change help to reflect possibility of editing md files

bb.sh

@@ -957,7 +957,7 @@ echo ""
 echo "Commands:"
 echo "    post [-m] [filename]    insert a new blog post, or the filename of a draft to continue editing it"
 echo "                            use '-m' to edit the post as Markdown text"
-echo "    edit [-n|-f] [filename] edit an already published .html file. **NEVER** edit manually a published .html file,"
+echo "    edit [-n|-f] [filename] edit an already published .html or .md file. **NEVER** edit manually a published .html file,"
 echo "                            always use this function as it keeps internal data and rebuilds the blog"
 echo "                            use '-n' to give the file a new name, if title was changed"
 echo "                            use '-f' to edit full html file, instead of just text part (also preserves name)"