Update runtime files
diff --git a/runtime/ftplugin/jsonnet.vim b/runtime/ftplugin/jsonnet.vim
new file mode 100644
index 0000000..1e621e1
--- /dev/null
+++ b/runtime/ftplugin/jsonnet.vim
@@ -0,0 +1,17 @@
+" Vim filetype plugin
+" Language: Jsonnet
+" Maintainer: Cezary Drożak <cezary@drozak.net>
+" URL: https://github.com/google/vim-jsonnet
+" Last Change: 2022-09-08
+
+" Only do this when not done yet for this buffer
+if exists("b:did_ftplugin")
+ finish
+endif
+
+" Don't load another plugin for this buffer
+let b:did_ftplugin = 1
+
+setlocal commentstring=//\ %s
+
+let b:undo_ftplugin = "setlocal commentstring<"