feat(chore): fix cdn default js file

The main property in package.json misses the file extension. jsdelivr needs the file extension, otherwise it does not recognize the default file. It's also advised by npm to include the file extension.

Author: lubber-de

package.json

@@ -18,7 +18,7 @@
   },
   "license": "MIT",
   "author": "Jack Lukic <[email protected]>",
-  "main": "dist/semantic",
+  "main": "dist/semantic.js",
   "repository": {
     "type": "git",
     "url": "https://github.com/fomantic/Fomantic-UI.git"