Fix inconsistent capitalization.

Amit Langote

Discussion: http://postgr.es/m/a83a0899-19f5-594c-9aac-3ba0f16989a1@lab.ntt.co.jp

src/backend/commands/tablecmds.c

@@ -13779,7 +13779,7 @@ ATExecAttachPartition(List **wqueue, Relation rel, PartitionCmd *cmd)
 	 * Prevent circularity by seeing if rel is a partition of attachrel. (In
 	 * particular, this disallows making a rel a partition of itself.)
 	 *
-	 * We do that by checking if rel is a member of the list of attachRel's
+	 * We do that by checking if rel is a member of the list of attachrel's
 	 * partitions provided the latter is partitioned at all.  We want to avoid
 	 * having to construct this list again, so we request the strongest lock
 	 * on all partitions.  We need the strongest lock, because we may decide