fix(exists-method): fix method syntax with an alias

Author: chloelbn

lib/algolia/index.rb

@@ -1295,6 +1295,11 @@ def exists
       return true
     end
 
+    #
+    # Aliases the exists method
+    #
+    alias :exists? :exists
+
     # Deprecated
     alias_method :get_user_key, :get_api_key
     alias_method :list_user_keys, :list_api_keys

spec/client_spec.rb

@@ -177,12 +177,12 @@ def wait_global_key_missing(key)
 
   it "should tell if index exists" do
     @index.add_object!({ :name => "John Doe", :email => "[email protected]" }, "1")
-    expect(@index.exists).to be true
+    expect(@index.exists?).to be true
   end
 
   it "should tell if index does not exist" do
     index = Algolia::Index.new('nonexistent_index')
-    expect(index.exists).to be false
+    expect(index.exists?).to be false
   end
 
   it "should add a simple object" do