fetchChannelsByDescription
Fetches channels by their description.
This API performs an asynchronous search for channels whose description contains the provided topic
. The search will return all channels whose description matches or partially matches the given topic
. The result is wrapped in a RainbowResult to indicate success or failure.
Return
A RainbowResult containing a list of Channel objects whose description matches the given topic
. In case of failure, the result will contain error details.
Parameters
topic
The topic or part of the description to search for in channels.