Update rocketchat.mdx

[lestercoyoyjr]

Add most recent official documentation from Rocke.Chat about Rasa.

Proposed changes:

• ...

Status (please check what you already did):

• [ ] added some tests for the functionality
• [ ] updated the documentation
• [ ] updated the changelog (please check changelog for instructions)
• [ ] reformat files using black (please check Readme for instructions)

[CLAassistant]

All committers have signed the CLA.

[vcidst]

@lestercoyoyjr Are you aware if the instructions in the documentation still work for RocketChat? I believe that this notice can be added to the top of the documentation page