Fix comment in heap.c
The description of InsertPgAttributeTuple() does not match its handling
of pg_attribute contents with NULL values for a long time, with
making things more inconsistent.  This adjusts the description to match
the reality.
Author: Daniel Gustafsson
Discussion:
@@ -714,8 +714,8 @@ CheckAttributeType(const char *attname,
* Construct and insert a new tuple in pg_attribute.
*
* Caller has already opened and locked pg_attribute. new_attribute is the
- * attribute to insert. attcacheoff is always initialized to -1, attacl and
- * attoptions are always initialized to NULL.
+ * attribute to insert. attcacheoff is always initialized to -1, attacl,
+ * attfdwoptions and attmissingval are always initialized to NULL.
*
* indstate is the index state for CatalogTupleInsertWithInfo. It can be
* passed as NULL, in which case we'll fetch the necessary info. (Don't do
