Update package.json (#121)

The main entry point should be 'src' rather than 'src/init'

-ensures that the correct entry file is used when the package is imported or executed.

package.json

@@ -2,7 +2,7 @@
     "name": "@rbxts/jecs",
     "version": "0.3.0-rc.1",
     "description": "Stupidly fast Entity Component System",
-    "main": "src/init",
+    "main": "src",
     "repository": {
         "type": "git",
         "url": "https://github.com/ukendio/jecs.git"