update extension activationEvents

Author: Brad Cornes

packages/tailwindcss-vscode/package.json

@@ -17,7 +17,7 @@
     "vscode": "^1.33.0"
   },
   "activationEvents": [
-    "onLanguage:plaintext"
+    "workspaceContains:**/{tailwind,tailwind.config,tailwind-config,.tailwindrc}.js"
   ],
   "main": "dist/src/extension/index.js",
   "contributes": {