Update syntax files for vim (#2039)
Set comments and commentstring.
These variables are documented e.g. [here](https://vimhelp.org/options.txt.html#%27comments%27).
For comparison other language plugins also set these two variables [vim-go](https://github.com/fatih/vim-go/blob/master/ftplugin/go.vim#L22) or [vim-toml](https://github.com/cespare/vim-toml/blob/main/ftplugin/toml.vim#L18).
I used these variables through the [tcomment](https://github.com/tomtom/tcomment_vim) plugin. e.g. gcc toggles whether the current line is commented in or out. Also standard vim folding (mark a section and hit zf appears affected by these settings).
pseyfert