The term `parameter` is a better word than `argument` for data passed
to an API endpoint; this is why OpenAPI uses in their terminology.
Replace `argument` with `parameter` in the API docs to improve their
readability.
Fixes#15435.
Firstly, change endpoint descriptions in zulip.yaml so that they
match their counterpart in the api docs. Then edit the api docs
so that they use api description markdown extension for displaying
endpoint description.
orientor
Vishnu Ks
sameerchoubey