Document the Map function in the documentation #11435
Description
Is your feature request related to a problem or challenge?
We implemented map and make_map functions in #1136. We're better to have the corresponding documentation for them.
Describe the solution you'd like
As @alamb mentioned in #11361 (review), we can follow the https://datafusion.apache.org/user-guide/sql/scalar_functions.html#struct-functions to do it.
Describe alternatives you've considered
No response
Additional context
No response