Address review suggestions

examples/on-conflict-clause/on_conflict_clause.bal

@@ -14,15 +14,15 @@ public function main() {
         ];
 
     // The result of the following will be an error since the key `John` is duplicated
-    // and `isSafeReplace()` function returns an error for the name `John`
+    // and `isSafeReplace()` function returns an error for the name `John`.
     map<int>|error studentScores = map from var {name, score} in students
                                    select [name, score]
                                    on conflict isSafeReplace(name);
 
     io:println(studentScores);
 
     // The result of the following will be an error since the key `1` is duplicated
-    // and `isSafeReplace()` function returns an error for the name `John`
+    // and `isSafeReplace()` function returns an error for the name `John`.
     table<Student> key(id)|error studentScoresTable = table key(id) from var student in students
                                                       select student
                                                       on conflict isSafeReplace(student.name);
@@ -36,15 +36,15 @@ public function main() {
         ];
 
     // The value `100` of the key `Mike` will be replaced by the second occurrence value `200`
-    // since `isSafeReplace()` function returns `null` for the name 'Mike`
+    // since `isSafeReplace()` function returns `null` for the name 'Mike`.
     map<int>|error lastRoundScore = map from var student in students2
                                     select [student.name, student.score]
                                     on conflict isSafeReplace(student.name);
 
     io:println(lastRoundScore);
 
     // The return value will be just the construct type if the `on conflict` clause
-    // always returns `()`
+    // always returns `()`.
     map<int> lastRoundScore2 = map from var student in students2
                                select [student.name, student.score]
                                on conflict ();