Update runtime files
diff --git a/runtime/ftplugin/livebook.vim b/runtime/ftplugin/livebook.vim
new file mode 100644
index 0000000..c97d210
--- /dev/null
+++ b/runtime/ftplugin/livebook.vim
@@ -0,0 +1,9 @@
+" Placeholder livebook filetype plugin file.
+" This simply uses the markdown filetype plugin.
+
+" Only load this plugin when no other was loaded.
+if exists("b:did_ftplugin")
+    finish
+endif
+
+runtime! ftplugin/markdown.vim ftplugin/markdown_*.vim ftplugin/markdown/*.vim