feat(policies): add CommentPolicy, update? and LikePolicy

examples/blog/app/policies/post_policy.rb

@@ -0,0 +1,13 @@
+class PostPolicy < Prism::Policy
+  def update?
+    user && record.user_id == user.id
+  end
+
+  def destroy?
+    update?
+  end
+
+  def restore?
+    update?
+  end
+end