Adding .cfg files syntax highlighting
### Problem to solve
Hello, I am not quite sure if this is the place but I might as well post. GitHub currently have syntax highlighting for ".cfg" files. What is a ".cfg" file you asked? It's a configuration file, commonly use in both softwares and games. I personally prefer GitLab over GitHub and I went to upload my code and noticed that there was no highlighting to it. (Sorry if I leave some information out, I wasn't't exactly sure on how to answer some questions apart of the template)
### Intended users
This feature would be use by both developers and gamers. As a very serious gamer, especially for Counter Strike, I would like to have my configuration files uploaded to GitLab which isn't a problem. But as a programmer and software developer, it hurts my eyes to read unhighlighted code. This feature would also be use by system administrators as `.cfg` is commonly use on servers, especially game servers.
### Proposal
I do not know much about GitLab code as I only took a look at it but I would assume this feature would not be that hard to implement. If I was implementing it I would prob use `highlights.js` since its a very powerful library to do just that. However I am sure the developers of GitLab have a better way of dealing with it.
### Links / references
An example of the file on GitHub: https://github.com/devKurieita/csgo_config/blob/master/keybinds.cfg
An example of the file on GitLab: https://gitlab.com/kurieita/csgo-config/blob/master/keybinds.cfg
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