Update troubleshooting (#109)

Add hint to check CSS package being enabled.

caused by https://forum.sublimetext.com/t/no-scss-syntax-highlighting-solved/72174

README.md

@@ -22,9 +22,18 @@ The easiest way to install is using [Package Control](https://packagecontrol.io)
 
 SCSS extends Sublime Text's CSS syntax definition as of ST4149.
 
-If SCSS syntax highlighting doesn't work and console displays syntax errors, please make sure to remove any out-dated syntax override.
+If SCSS syntax highlighting doesn't work and console displays syntax errors, 
 
-Steps:
+1. check if CSS package enabled.
+2. remove any out-dated syntax override.
+
+### Enable CSS package
+
+1. Open `Command Palette` using <kbd>ctrl+shift+P</kbd> or menu item `Tools → Command Palette...`
+2. Choose `Package Control: Enable Packages`
+3. Find `CSS` and hit <kbd>Enter</kbd>
+
+### Remove overrides
 
 1. call _Menu > Preferences > Browse Packages.._
 2. Look for _CSS_ folder