Add POST /api/v1/notifications/:id/dismiss (#8905)

POST /api/v1/notifications/dismiss was a mistake in #2251

config/routes.rb

@@ -296,6 +296,10 @@ Rails.application.routes.draw do
       resources :notifications, only: [:index, :show] do
         collection do
           post :clear
+          post :dismiss # Deprecated
+        end
+
+        member do
           post :dismiss
         end
       end