ruby: 0002-looping.rb: add looping references
ruby: 0002-looping.rb: add looping references

This commit is to add looping referneces note.

Signed-off-by: Holloway, Kean Ho <bbd8faa40b0f348214bf4124b281a301299ba6dd@gmail.com>

hollowaykeanho/learning,hollowaykeanho/learning,hollowaykeanho/learning,josiahsoh/learning,hollowaykeanho/learning,josiahsoh/learning,hollowaykeanho/learning,josiahsoh/learning,josiahsoh/learning,josiahsoh/learning