Changes to Join an existing swarm

removed the request body

removed the success response with the status 204

api tag Swarm added

added the non-success response with the status 400

added the non-success response with the status 500

added the non-success response with the status 503

added the success response with the status 200

removed the media type text/plain from the request body

removed the success response with the status 200

api tag Swarm removed

removed the non-success response with the status 400

removed the non-success response with the status 500

removed the non-success response with the status 503

added the success response with the status 204

added required request body

added the media type application/json for the response with the status 400

added the media type application/json for the response with the status 500

added the media type application/json for the response with the status 503