[vim] update Racket settings, default fold level

.vim/after/ftplugin/racket.vim

@@ -1 +1,3 @@
-au VimEnter * RainbowToggleOn
+au BufEnter * RainbowToggleOn
+setlocal foldmethod=syntax
+setlocal lispwords+=define-macro,syntax/loc,with-handlers,with-pattern

.vimrc

@@ -48,7 +48,7 @@ call s:highlight()
 " highlight LongLine term=reverse cterm=reverse ctermfg=1 guifg=Black guibg=Yellow
 " match LongLine /\%101v./
 
-set foldlevelstart=6
+set foldlevelstart=10
 set foldmethod=indent
 set linebreak
 set list