Add missing content and fix typos in comments

Author: hantangwangd

presto-main-base/src/main/java/com/facebook/presto/sql/planner/iterative/Lookup.java

@@ -26,7 +26,7 @@ public interface Lookup
     /**
      * Resolves a node by materializing GroupReference nodes
      * representing symbolic references to other nodes. This method
-     * is deprecated since is assumes group contains only one node.
+     * is deprecated since it assumes group contains only one node.
      * <p>
      * If the node is not a GroupReference, it returns the
      * argument as is.

presto-main-base/src/main/java/com/facebook/presto/sql/planner/iterative/rule/LeftJoinWithArrayContainsToEquiJoinCondition.java

@@ -48,7 +48,7 @@
 import static java.util.Objects.requireNonNull;
 
 /**
- * When the join condition of a left join has pattern of contains(array, element) where array, we can rewrite it as a equi join condition. For example:
+ * When the join condition of a left join has pattern of contains(array, element) where array is from the right-side relation and element is from the left-side relation, we can rewrite it as an equi join condition. For example:
  * <pre>
  * - Left Join
  *      empty join clause