Task: Post a message to a channel in RocketChat

n8n workflow:
{"id":"90","name":"Post a message to a channel in RocketChat","nodes":[{"name":"On clicking 'execute'","type":"n8n-nodes-base.manualTrigger","position":[250,300],"parameters":{},"typeVersion":1},{"name":"Rocketchat","type":"n8n-nodes-base.rocketchat","position":[450,300],"parameters":{"text":"Hello everyone","channel":"#general","options":{},"attachments":[]},"credentials":{"rocketchatApi":"Rocket"},"typeVersion":1}],"active":false,"settings":{},"connections":{"On clicking 'execute'":{"main":[[{"node":"Rocketchat","type":"main","index":0}]]}}}