Fix pg_description entries for jsonb_to_record() and jsonb_to_recordset().

All the other jsonb function descriptions refer to the arguments as being
"jsonb", but these two said "json".  Make it consistent.  Per bug #13905
from Petru Florin Mihancea.

No catversion bump --- we can't force one in the back branches, and this
isn't very critical anyway.

src/include/catalog/pg_proc.h

@@ -4745,9 +4745,9 @@ DESCR("get record fields from a jsonb object");
 DATA(insert OID = 3475 (  jsonb_populate_recordset	PGNSP PGUID 12 1 100 0 0 f f f f f t s s 2 0 2283 "2283 3802" _null_ _null_ _null_ _null_ _null_ jsonb_populate_recordset _null_ _null_ _null_ ));
 DESCR("get set of records with fields from a jsonb array of objects");
 DATA(insert OID = 3490 (  jsonb_to_record			PGNSP PGUID 12 1 0 0 0 f f f f t f s s 1 0 2249 "3802" _null_ _null_ _null_ _null_ _null_ jsonb_to_record _null_ _null_ _null_ ));
-DESCR("get record fields from a json object");
+DESCR("get record fields from a jsonb object");
 DATA(insert OID = 3491 (  jsonb_to_recordset		PGNSP PGUID 12 1 100 0 0 f f f f f t s s 1 0 2249 "3802" _null_ _null_ _null_ _null_ _null_ jsonb_to_recordset _null_ _null_ _null_ ));
-DESCR("get set of records with fields from a json array of objects");
+DESCR("get set of records with fields from a jsonb array of objects");
 DATA(insert OID = 3210 (  jsonb_typeof				PGNSP PGUID 12 1 0 0 0 f f f f t f i s 1 0 25 "3802" _null_ _null_ _null_ _null_ _null_ jsonb_typeof _null_ _null_ _null_ ));
 DESCR("get the type of a jsonb value");
 DATA(insert OID = 4038 (  jsonb_ne		   PGNSP PGUID 12 1 0 0 0 f f f f t f i s 2 0 16 "3802 3802" _null_ _null_ _null_ _null_ _null_ jsonb_ne _null_ _null_ _null_ ));