Fix incorrect comment.

Etsuro Fujita

Discussion: http://postgr.es/m/5A05728E.4050009@lab.ntt.co.jp

Author: robertmhaas

src/backend/optimizer/util/relnode.c

@@ -676,8 +676,7 @@ build_join_rel(PlannerInfo *root,
  * 'sjinfo': child-join context info
  * 'restrictlist': list of RestrictInfo nodes that apply to this particular
  *		pair of joinable relations
- * 'join_appinfos': list of AppendRelInfo nodes for base child relations
- *		involved in this join
+ * 'jointype' is the join type (inner, left, full, etc)
  */
 RelOptInfo *
 build_child_join_rel(PlannerInfo *root, RelOptInfo *outer_rel,