add YARD docs to Faker::SlackEmoji (#1956)

* add YARD docs to Faker::SlackEmoji

* Update lib/faker/default/slack_emoji.rb

Co-authored-by: Koichi ITO <koic.ito@gmail.com>

* Update lib/faker/default/slack_emoji.rb

Co-authored-by: Stephen A. Wilson <stephen-356@hotmail.com>
Co-authored-by: Koichi ITO <koic.ito@gmail.com>

lib/faker/default/slack_emoji.rb

@@ -3,38 +3,119 @@
 module Faker
   class SlackEmoji < Base
     class << self
+      ##
+      # Produces a random slack emoji from people category.
+      #
+      # @return [String]
+      #
+      # @example
+      #   Faker::SlackEmoji.people #=> ":sleepy:"
+      #
+      # @faker.version 1.5.0
       def people
         fetch('slack_emoji.people')
       end
 
+      ##
+      # Produces a random slack emoji from nature category.
+      #
+      # @return [String]
+      #
+      # @example
+      #   Faker::SlackEmoji.nature #=> ":mount_fuji:"
+      #
+      # @faker.version 1.5.0
       def nature
         fetch('slack_emoji.nature')
       end
 
+      ##
+      # Produces a random slack emoji from food and drink category.
+      #
+      # @return [String]
+      #
+      # @example
+      #   Faker::SlackEmoji.food_and_drink #=> ":beers:"
+      #
+      # @faker.version 1.5.0
       def food_and_drink
         fetch('slack_emoji.food_and_drink')
       end
 
+      ##
+      # Produces a random slack emoji from celebration category.
+      #
+      # @return [String]
+      #
+      # @example
+      #   Faker::SlackEmoji.celebration #=> ":tada:"
+      #
+      # @faker.version 1.5.0
       def celebration
         fetch('slack_emoji.celebration')
       end
 
+      ##
+      # Produces a random slack emoji from activity category.
+      #
+      # @return [String]
+      #
+      # @example
+      #   Faker::SlackEmoji.activity #=> ":soccer:"
+      #
+      # @faker.version 1.5.0
       def activity
         fetch('slack_emoji.activity')
       end
 
+      ##
+      # Produces a random slack emoji from travel and places category.
+      #
+      # @return [String]
+      #
+      # @example
+      #   Faker::SlackEmoji.travel_and_places #=> ":metro:"
+      #
+      # @faker.version 1.5.0
       def travel_and_places
         fetch('slack_emoji.travel_and_places')
       end
 
+      ##
+      # Produces a random slack emoji from objects and symbols category.
+      #
+      # @return [String]
+      #
+      # @example
+      #   Faker::SlackEmoji.objects_and_symbols #=> ":id:"
+      #
+      # @faker.version 1.5.0
       def objects_and_symbols
         fetch('slack_emoji.objects_and_symbols')
       end
 
+      ##
+      # Produces a random slack emoji from custom category.
+      #
+      # @return [String]
+      #
+      # @example
+      #   Faker::SlackEmoji.custom #=> ":slack:"
+      #
+      # @faker.version 1.5.0
       def custom
         fetch('slack_emoji.custom')
       end
 
+      ##
+      # Produces a random slack emoji from any category.
+      #
+      # @return [String]
+      #
+      # @example
+      #   Faker::SlackEmoji.emoji #=> ":pizza:"
+      #
+      # @faker.version 1.5.0
       def emoji
         parse('slack_emoji.emoji')
       end