Create guide object from .md file.
Language to use for guide
The base URL for assets
A promise that resolves with the guide object, or undefined on error
When the request exceeds the timeout duration (propagated from Fetch.fetchText())
Fetch.fetchText()
When the request was aborted by the caller's signal (propagated from Fetch.fetchText())
When the response is not OK / non-2xx (propagated from Fetch.fetchText())
When the text response is empty (propagated from Fetch.fetchText())
When a network issue happened (propagated from Fetch.fetchText())
Create guide object from .md file.