Doc: fix parameter names in the docs of a couple of functions.

Doc: fix parameter names in the docs of a couple of functions.

The descriptions of make_interval() and pg_options_to_table()
were randomly different from the reality embedded in pg_proc.

(These are not all the discrepancies I found in a quick search,
but the others perhaps require more discussion, since there's
at least a case to be made for changing pg_proc not the docs.)

make_interval issue noted by Thomas Kellerer.

Discussion: https://postgr.es/m/7b154ef0-9f22-90b9-7734-4bf23686695b@gmx.net