Adds slack order notification

packages/medusa-plugin-slack-notification/.eslintrc

@@ -0,0 +1,9 @@
+{
+  "plugins": ["prettier"],
+  "extends": ["prettier"],
+  "rules": {
+    "prettier/prettier": "error",
+    "semi": "error",
+    "no-unused-expressions": "true"
+  }
+}