Merge branch '24915_merge_slash_command' into 'master'

app/assets/javascripts/notes.js

app/controllers/projects/merge_requests_controller.rb

app/controllers/projects/notes_controller.rb

app/helpers/merge_requests_helper.rb

app/models/merge_request.rb

app/services/merge_requests/update_service.rb

app/services/notes/create_service.rb

app/services/notes/slash_commands_service.rb

app/services/slash_commands/interpret_service.rb

app/views/projects/merge_requests/_show.html.haml

app/views/projects/notes/_form.html.haml

changelogs/unreleased/24915_merge_slash_command.yml

config/routes/project.rb

doc/user/project/slash_commands.md

spec/controllers/projects/merge_requests_controller_spec.rb

spec/controllers/projects/notes_controller_spec.rb

.../features/merge_requests/user_uses_slash_commands_spec.rb

spec/helpers/merge_requests_helper_spec.rb

spec/models/merge_request_spec.rb

spec/services/merge_requests/update_service_spec.rb