DOC: Fix non-standard Input/Output docstring section management (#3505)

## Changes proposed in this pull request

Fix non-standard Input/Output docstring section management: map `Inputs`
and `Outputs` to `params_style` and `returns_style`, respectively, for
`napoleon` custom sections (instead of mapping them to `Parameters`).

Documentation:

https://www.sphinx-doc.org/en/master/usage/extensions/napoleon.html#confval-napoleon_custom_sections


## Documentation that should be reviewed

Any workflow function.

Author: effigies

docs/conf.py

@@ -69,8 +69,8 @@
 # https://github.com/sphinx-contrib/napoleon/pull/10 is merged.
 napoleon_use_param = False
 napoleon_custom_sections = [
-    ('Inputs', 'Parameters'),
-    ('Outputs', 'Parameters'),
+    ('Inputs', 'params_style'),
+    ('Outputs', 'returns_style'),
 ]
 
 # The suffix(es) of source filenames.