Hopefully you've solved this issue by now, but to install this via Package Control (https://packagecontrol.io/installation
), simply follow these steps:
1a. Windows or Linux: press ctrl+shift+p
1b. Mac: press cmd+shift+p
2. Type "Package Control: Install Package" and press enter/return.
3. Wait for the new dropdown and then type "Ruby Slim" and press enter/return.
4. At the very bottom right of the Sublime text editor, click on the language and select "Ruby Slim".