Rename `ReactionController` to `ReactionsController`

app/controllers/reactions_controller.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-class ReactionController < ApplicationController
+class ReactionsController < ApplicationController
   def index
     answer = Answer.includes([smiles: { user: :profile }]).find(params[:id])
 

config/routes.rb

@@ -155,7 +155,7 @@ Rails.application.routes.draw do
   post "/@:username/a/:id/pin", to: "answer#pin", as: :pin_answer
   delete "/@:username/a/:id/pin", to: "answer#unpin", as: :unpin_answer
   get "/@:username/a/:id/comments", to: "comment#index", as: :comments
-  get "/@:username/a/:id/reactions", to: "reaction#index", as: :reactions
+  get "/@:username/a/:id/reactions", to: "reactions#index", as: :reactions
   get "/@:username/q/:id", to: "question#show", as: :question
   get "/@:username/c/:id/reactions", to: "comment#show_reactions", as: :comment_reactions
   get "/@:username/followers", to: "user#followers", as: :show_user_followers

spec/controllers/reactions_controller_spec.rb

@@ -2,7 +2,7 @@
 
 require "rails_helper"
 
-describe ReactionController, type: :controller do
+describe ReactionsController, type: :controller do
   describe "#index" do
     shared_examples_for "succeeds" do
       it "returns the correct response" do